Idle Invaders (justking14)

Aliens have begun their invasion and loss is inevitable, but thankfully humanity is as stubborn as they are lazy and have built an AI to fight for them.  

It will eventually be overrun, but slain enemies drop coins that can be used to purchase upgrades and these coins carry over between runs.

M-opens up the skill tree menu

Arrows-navigate through the skill tree menu

Enter-purchase selected upgrade