Secret Agent ftw! Wacky Wheels! Commander Keen!
My dad introduced me to Keen, Prince of Persia (and other classics like Doom and Wolfenstein etc.) when I was tiny.
I still recall how he contrasted the comical/arcade-y movement in Keen to the "realistic" movement in PoP. I was 3 or 4 years old, mind. It was great to see this [1] on HN the other day - it led me to this [2] video which kind of served to explain to my dad and I how he got the movement so right. Sorry weird tangent.
Two other games I remember enjoying was The Incredible Machine and Chip's Challenge. TIM was amazing! Must remember to dig that out if I ever have kids.
[1] https://news.ycombinator.com/item?id=32538026 [2] https://www.youtube.com/watch?v=Jbk5qH2-1S8
The first game I remember playing on my own is the first Commander Keen. I was very proud of being able to start and run it on my own from DOS (I was 3; using a text-only input mode is difficult when you're pre-literate!)
... also
* Raptor: Call of the Shadows.
* Magus.
* Jill of the jungle.
* Mystic Towers.
* Terminal Velocity.
The Psygnosis logo was legit the coolest thing I ever saw when I was single digit years old.
Ctrl - jump
Alt - pogo stick (after you obtained it)
Ctrl Alt (pressed at the same time) - fire blaster
If you did not time it well you could end up doing an "advanced" pogo high jump (by pressing Alt just before Ctrl) when you intended to zap a Vorticon.
Commander Keen 4 improved the controls with a dedicated fire button. It also had one of the best control schemes, gameplay, and art for that generation of platform games.
They're far enough back a lot of people won't be aware of them, yet modern enough they're still playable.