Frontier Elite (David Braben). A vast universe, with awesome space flight mechanics (gravity, etc), great graphics/audio, all fitting on one floppy disk. It was coded in assembly:

https://en.wikipedia.org/wiki/Frontier:_Elite_II

You could do the slingshot effect in it.

For older games, I would say the original Prince of Persia. I played it on an 8088 machine, and it was pretty impressive how he made the animations sophisticated and smooth.