The Ren'Py Visual Novel Engine
renpy.org
renpy.org
- It has all the basic featured you'd expect, ranging from proper backlogs, to key bindings, and much more. You'd be shocked how many VN developers think that they can just pop out an VN engine themselves, and end up producing something that lacks even basic features.
- It is performant. You'd be surprised how poorly many VN engines run really poorly. Fast-forwarding past already-read text is often capped at a surprisingly slow rate, with your CPU pegged at 100%, due to how inefficient many engines are
- It is easily moddable, as you just need to plop a (pseudo-)python script into the game folder, so you can easily tweak or turn off annoying bits of UI
A number of localization companies have also ported (typically older) Japanese titles to Ren'py, instead of having to struggle with poor to non-existent support for non-Japanese systems in the original engine, as well as extremely expensive engine licenses, and just straight up poorly written bespoke engines. Examples of companies having done this includes JAST USA, FAKKU, MangaGamer, and (IIRC) Sekai Project/Denpasoft. In other words, the heavy hitters of VN localization.
The other main contender for best VN engine (in my mind) is the KiriKiri engine, which I believe is also open source, but which lacks the large, English-speaking community that Ren'py has built.
Despite that, Ren'py does have a bit of a poor reputation in the older VN reading community, more specifically among readers who mainly read localized, Japanese VNs, due to its association with low-budget, originally English visual novels. Typically the same people have only heard of DDLC and Katawa Shoujo, when it comes to originally English visual novels
As far as competitors go, the list is not very long. Sugarcube/Twine works ok, but tends to bog down as the projects grow large because it doesn't have a good way of breaking up the core logic across different files. The save system is also a bit of a problem since the in-browser saves tend to get lost in version updates. QSP is just a buggy confusing mess every time. People try to shoehorn RPGMaker into doing the job but it is just so clunky and slow. Custom engines, typically built in Unity, are almost always massive resource hogs and lacking in one or more of the basic features Ren'Py provides by default. Plus there is just the community aspect of it, with Ren'Py having so many developers there is a lot of institutional knowledge to be had. If you run into a problem you are probably not the first, someone else has probably solved it already.
This is of course not an exact ranking, since the same game can have many (nearly identical) releases, but it roughly matches my experience
In practice graph matching can be helped by manually tagging the same nodes (labels in Ren'Py) in the two versions, but that cannot cover all the edge cases
I'm developing a VN framework for the own use of my indie VN dev group, and we mostly implemented the diff algorithm for the 'linear' part of the graphs. You can search my handle to know more
You can make sure to be forward compatible by (1) never removing states, and (2) making sure that any state x (value of persistent variables) has a transition.
Of course, that condition (2) is often violated by assuming that if you are in state Si, you must have gone through state Sk which sets a given variable to x, and fail to realize that there is another path to Si that does not go through Sk and you are stuck. If you add new states or new variables to your game, you are effectively creating this situation for all states. Reachability is a trivial problem, but checking the values all variables can take is kind of famously Turing-complete. So if you want to be able to do that, you need your use of variables so that basically you could eliminate them by replacing them by having more states.
Btw, the problem you mention is a notoriously painful one (https://en.wikipedia.org/wiki/Graph_isomorphism_problem), but with VNs you have labels so I think the issue is not to produce a diff but make it useful enough to check all game conditions.
Let me know if something is unclear.
For example, if the script loops through a node (and there is a choice to go out of the loop), and the node moves a character on screen to the left by 5 pixels each time, then there can be different game states with the same node. It happens in a common trope of VNs when the story lets you explore different places and go back to the original place each time
In the design of our VN framework, the game state is determined not by the current node, but by the node history (and other things like 'global variables'). If the author changes some script in the new version, then all saved data with the affected node history need to get updated
If there is no choice added/deleted, then the update can be implemented by simply re-running the nodes. However, if there are choices added/deleted, the update can be more complicated and involve graph isomorphism in the worst case
Sure. I would say it's a pretty bad idea though, and for instance in JOBifAI we manually managed savepoints in these case to stay isomorphic to a DFA anyway, because it's already hard enough to manage when the game has a big scope.
>If there is no choice added/deleted, then the update can be implemented by simply re-running the nodes. However, if there are choices added/deleted, the update can be more complicated and involve graph isomorphism in the worst case
Well. what you call 'global variables' is what I called 'persistent variables' above (using renPy's terminology). If you consider that they can get any value, your problem can be reduced to the halting problem. There are 2 ways you can get around that:
- any use of these variables in conditional transitions segments the domain into a finite number of subdomains (in that case it's just a proxy for a long expansion into a much bigger DFA)
- the variables belong to an infinite domain but are not involved into any state transition (for example, setting your name is not restricted but does not change any state transition)
Since the halting problem isn't solvable, if you use these two solutions you don't need to solve the graph isomorphism problem. If you delete a node Si and your history contained Ss => Si => Se, you just need to find a path from Ss ==> Se. If you take the first in lexicographic order you even have a canonical solution.
In your indie VN dev group, are there any devs working on cross-platform, parser & choice-based VNs (ie I can read a work on mobile as choice-based, but if I want to continue that same save on my computer/ enter commands, I can do that)?
Especially when you increase the window size or run fullscreen, most VN engines just render the whole game at a fixed resolution and upscale it up but Renpy makes the framebuffer match the window size and renders text at the full resolution.
Something noticeably missing from almost every other type of text-heavy game which perhaps wouldn't be if games developers were less snobbish about where they draw inspiration from.
On the other hand, writers of games with metatextual stories benefit from their target audience not knowing how well-trod the ground is.
That caught my curiosity, but I couldn't find any examples of older VNs being ported to Renpy. Could you share any examples?
But if there are no titles that have already caught your interest, then my personal recommendation is to start with hybrid games such as VA-11 Hall-A, the Danganronpa series, the Ace Attorney series, WILL: A Wonderful World, and 999.
VNs are at their core a reading experience, frequently involving more words than what you'll find in the entire Lords of the Ring trilogy, but hybrid games like the above allow you to dip your toes in the VN genre without it purely being reading
In many ways I felt that the engine was designer for beginners rather than developers in a way that are antagonistic to each others. No real debugger, no support for libraries, leading to re-implementation of basic stuff, etc. I had a love-hate relationship with it. Pseudo-python is the right term for it.
In the end I was happy with the Steam features it already had to make distribution easy, although I had to actually patch the engine as the Steam session ticket function was broken.
All that to say, you probably won't like VNs unless you like reading. Don't expect much gameplay / animation. That said, the more famous stories tend to have multiple endings determined by a handful of choices you get during the story. On occasion, some games go for sandbox-style gameplay where you roam the map to grind out currency to unlock visual novel scenes.
In terms of genre I'd say at least half are dating sims, with the rest being some kind of adventure or mystery story. I'd also guess at least half are nsfw / r18. Renpy VNs tend to be made by indie devs from everywhere but Japan, which has a VN industry with in-house engines.
Writing quality tends to be what you expect from indie authors / devs. That is, filled with tropes, tending towards the wish-fulfillment types. Which isn't necessarily a bad thing, you'll be surprised what you'd be willing to overlook if the premise / plot seems interesting.
Usually, but some of them are infamously ludicrously long. Like 2-3x War and Peaces long.
Looks like the median renpy novel (with 100+ votes) takes 250min to complete with the ludicrously long ones [2] bringing the average up to 503min.
engine vn count avg 25% 50% 75%
Ren'Py 251 503 120 251 571
KiriKiri 187 813 241 522 1143
Unity 65 871 224 452 1109
[2] https://query.vndb.org/?sql=SELECT%0D%0Avn.title%2C%0D%0AROU...
title length (min) engine
HEAVEN BURNS RED 12580 CRIware
Rance X -Kessen- 11085 AliceSoft System4.X
Shoujo Settai 10418
Kamidori Alchemy Meister 8407
Seinarukana... 6858
Lessons in Love 6819 Ren'Py
Sengoku † Koihime... 6744 CatSystem2
Higurashi no Naku Koro ni 6626Off the top of my head, hybrid VNs on your list includes HEAVEN BURNS RED, Rance X, Kamidori, Seinarukana, and Koihime. Though as far as I know, Rance X in particular also has a very, very long script
laughs in umineko and higurashi
Some if the entries really push the limits in terms visual presentation and can have a crazy amounts of animations. Plus really talented voice actors use the jam to practice their skills.
Unfortunately, Japan stopped making visual novels somewhere around a decade ago. Creators presumably moved on to work on gacha games. Many visual novel companies are now either gone, inactive, or pivoted to gacha games. I wish I can see more games like Baldr Sky, Steins Gate, and Aiyoku no Eustia again.
It feels to me like 'Hate Story' and its sequel ('Hate Plus') really pushed the bounds of what a visual novel engine can easily do.
Needy Streamer Overload was the big visual novel of 2024 I think, which was Unity.
The most popular modern-ish visual novels I know of, like Fate Grand Order, Dangenronpa, and Ace Attorney, aren't Ren'py.
I feel like Ren'py is in the minority for modern popular visual novels, and it's definitely in the minority if you include re-releases of older visual novels.
I'd expect it to be in the vast majority for independent visual novels.
Then I dug a little deeper and saw that a lot of it is very sexualized. I'm not opposed to that for adults but it isn't something I want my daughter exposed to.
Anyone have suggestions for safe spaces for kids? I really love the idea of her creating using ren'py but I'm worried it is a gateway to things she isn't ready for yet.
https://vndb.org/v?q=&ch=&f=02N1802a48a23N19a38&s=26y
Though I will caution that a lot of these are either self-reported by the authors or just guesstimates by the person who added the VN to VNDB.
And I will caution that you should never trust it when a visual novel is described as "all ages": For whatever reason, the VN reading community has settled on using that term when we mean "no explicit sexual content". Beyond that, anything goes for an "all ages" VN. The search link above has a minimum age rating of 3+ for that reason
I would recommend something like Scratch. It's a visual scripting language that allows kids to make amazing games and animations. It has all the capabilities necessary with ease and kid-friendly forums and comment sections.
Here it is on Steam, currently on sale for a criminally under priced $4.39
Interesting read/play, but not for everyone.
[1] https://en.m.wikipedia.org/wiki/Katawa_Shoujo
.
.
.
.
[2] does a 180 and makes fun of the plot holes
I guess "bad endings" and "save then go back" would be specific and played with in DDLC, but I didn't pick up anything else.
> So you kind of need familiarity with the genre to understand some of the jokes.
>> what are some tropes which are specific to dating sims rather than those also found in romance-based anime/manga?
It's been a while since I've read DDLC but familiarity was probably too strong a word. Having expectations about how the story should develop and then having those subverted is a good chunk of the fun [1]. So skimming at least one dating sim vn is probably enough context. And anime / manga also cover most of that context / japan-isms that DDLC mocks (eg the school setting, the childhood friend / council prez / spoiled imouto archetypes).
To your question though, the VN-specific jokes are mostly about the route system and world building. I guess these still fall under the umbrella of "bad endings" and "save then go back" but imo it's a huge umbrella that's worth exploring.
So like you mentioned, DDLC toys a lot with the concept of multiple routes / save files. In most VNs each route starts the same story before branching. You don't normally expect this "common route" to change between tries but in DDLC it does in multiple ways. But more uniquely, DDLC also questions why these romantic endings exist in the first place and arrives at the conclusion that the romantic interests are psychotically obsessed... by the design of some god [2]. This also pokes at how some VNs just rewrite the world between routes to avoid distractions from the chosen love interest, as in big events that are inevitable in one route just don't happen in others.
I also thought the choice system (the poems) in itself was a fun joke. Like most VNs have screens that let you vote on which route to read, one choice per route. After N screens you get placed on the route you picked most. DDLC exaggerates this by giving you 100s of screens each with multiple choices per love interest. Kind of like "Are you really really sure? Is this your final answer?"
Speaking of DDLC, I should really reread Totono [3]. It's another VN-parody but less gimmicky and a bit more serious / emotional.
[1] https://github.com/Bronya-Rand/DDLCModTemplate2.0/blob/v1.1....
[2] https://github.com/Bronya-Rand/DDLCModTemplate2.0/blob/69aa2...
https://github.com/Bronya-Rand/DDLCModTemplate2.0/blob/v1.1....
[3] https://store.steampowered.com/app/1293820/YOU_and_ME_and_HE...
I'd also include the (sometimes literally) faceless protagonists in this. For the uninitiated, it's a fairly common trope in romance VNs that the face of the protagonist is obscured, supposedly to let the player self-insert. In DDLC, if I recall correctly, you mostly see the protagonist's hands and in one image his back.
This trope leads to some fairly weird looking haircuts or (more commonly) to graphics where protagonists simply have no eyes. Perhaps fittingly, this also sometimes applies to characters that are so unimportant that they get labels such as "Student A" instead of proper names, if they even get sprites at all.
DDLC takes it to the logical conclusion that it is the player that matters, not the paper-thin player stand-in
I also remember expecting the story to comment on how, like most dating sims*, there's no male characters (or really any characters in DDLC's case) except for the MC and being disappointed it didn't. Well I think there were allusions to an abusive dad but again I don't think anyone had dialogue lines outside the MC + LIs.
* There are dating sims targeting other demographics like female MC + male LIs but DDLC was parodying the ones for males.
https://store.steampowered.com/app/2118420/Stories_from_Sol_...
(Warning: This site contains a lot of text and images that are not safe for work. And it records a lot of works that many people will probably find distressing)
https://vndb.org/v?q=&ch=&f=N1802fwRen_7Py-741&s=26y
But as you say, that's barely scratching the surface. You can probably find many more on itch.io and in other communities, that nobody have bothered to add to VNDB
But you can exclude those by only searching for official releases:
Edit: I don't have the patience for these games but yeah I've seen the name before
Some people point out this is mainly because of the erotic novel shovelware that is quite popular on Steam.
What does it do that Flash didn't?