Yep this game is very addictive, I remember play testing it to release fot the jam and suddenly I was 2 hours invested in and still had things to program.
About the upgrades here is a detailed version of them (and I probably gonna copy them on description later):
Mouse Minify Power -> Your clicks are more powerful so you can minify the Smolls faster
Critical Chance -> Add a Chance to Crit when Clicking (only clicking) so your "power output" get doubled if you crit ( a different noise plays when you click and crit)
Worker -> Add a Worker that helps you Minify the monsters. A worker can only work in 1 chamber at time, this means that you need 4 workers to have all 4 chambers going down at same time (depending on the number of unlocked chambers the workers are rearranged)
Perfurm -> Minify ALL the monsters. When the worker can only decrease a chamber at time the Perfum apply in all open chambers at same time.
Perfum Tonic -> Power-up your perfurm efficiency by 1% per Level
Extra Smoll -> Add a new Smoll