So yeah, the game is really fun. It would be great, if you could navigate the upgrade menu easier. Being able to zoom in the upgrade menu (and maybe even in the world) would be cool.
My strategy was to spawn as many workers as fast as possible, while they're worth their cost, and then let them run out of time. I found it somewhat annoying, when a super slow worker spawned, since I wasn't able to use up all of the "free worker" limit efficiently.
I also don't think you should be worried about using the word "death" instead of "retirement" ;)