Firstly, thanks so much to the community here. I've been really blown away by the positive reception my little game has got so far. Reading your reviews really does motivating me to keep grinding away at making this thing!
As several people have found out and commented there are some performance issues and memory leaks in the game. Sadly, these issues are in RPG Maker MV, the software used to create Mars Underground. The good news though, is that the developers are busily working on improving the software and addressing these problems so hopefully future builds of the game will run much better.