So basically it's a Node.js app built in CoffeeScript. I'm using node-twitter-api to subscribe to the bot's twitter notifications (https://bitbucket.org/sparklinlabs/gdevbot/src/tip/app.coffe...).
Whenever a tweet arrives, I check various stuff (is it a retweet? are multiple people mentioned? more than one hashtag?) to decide whether it's a command or it should just be ignored. If all checks out, I parse the tweet's text (https://bitbucket.org/sparklinlabs/gdevbot/src/tip/app.coffe...) into a command and relay it to the backend for processing (https://bitbucket.org/sparklinlabs/gdevbot/src/tip/lib/backe...).
Images are validated & their size clamped using a node graphics-magick module. Emoji scripts are parsed using a custom parser I cobbled together (https://bitbucket.org/sparklinlabs/gdevbot/src/tip/public/js...) and JavaScript comes out on the other end.
The tiny game engine works with actors (or game objects in Unity3D parlance, it's very similar except 2D-only), they can have components (an image, one or more scripts) on them and can be parented to one another.
I've been building a cooperative game-making platform called CraftStudio (http://craftstud.io/) for the past 2-3 years and @gdevbot was just a kind of crazy "why the hell not" project inspired by all that work that I decided to build a couple weeks ago.