Problems with physics and huge universe

That definitely qualifies as an infinite universe in my book.

this game seems really cool

http://www.moddb.com/games/infinity-the-quest-for-earth

theres a gigantic galaxy, like hundreds of thousands of planets, stars wtv that are randomly generated

Computer numbers are always finite, even floating point.

You'll always have to devise some sort of trick to get infinity, in Construct or coding your own engine, so better stick with Construct

64-bit floats would be nice :D ...

Construct already uses 64-bit floats in the event engine. Positions, angles etc. are stored as 32 bit floats since that's generally all that's necessary for sufficient precision, and I think the Physics engine uses 32 bit floats as well, for efficiency.