You do know PowderToyLegacy is the same as normal tpt just faster on old computers?

Make a bunker or a city or a ship or a house or a planet or a bomb or a stkm level...

For more ideas:

https://powdertoy.co.uk/Discussions/Thread/View.html?Thread=17929&PageNum=1

Build a computer that interprets Python, and has a saving module! :D