Pressing esc (the usual method I used to pause) will exit the game, how do I pause without doing this after the 15 minute mark?

Game seemed to close itself shortly after I took this screenshot. https://steamcommunity.com/sharedfiles/filedetails/?id=3029500658 Perhaps there was too much stuff going on or something went wrong when trying to declare victory? I never had any crash before in my previous runs. Edit: my guess is that it has something to do with how t5 towers create vast amounts of projectiles/summons....

The mask seems quite strong. It is even relevant when one is getting purple tier towers because it is capable of making enemies go in reverse which is a far more effective barrier than walls. It might even be op. It is hard to say what exactly gold tier towers are supposed to fight, but the z-angle seems too strong. I got a mk 3 one and it wiped out the entire field by itself....

The wave gets stronger to fast while the units gets tiny upgrades, it can't keep up. Is there trick to it?

Have seen this game and tested. Like it. Are there still upgrades?