different skill trees (miner, researcher, technician, combatant, stuff like that)
when you do something associated to a skill tree, you get xp points, and when you get enough you gain a level in said skill tree, letting you buy a skill. when i say skill, i dont exactly mean "press e on somebody to do a backflip and snap their neck", but instead simple things like +10 mining speed. sometimes you wouldnt have an option of what skill to choose and be forced to choose 1 skill (to save precious development time)
once you gain a level in a skill tree, it takes more xp points to get another level. there would be 8-10 levels in each skill tree.
couple of examples
miner lvl 1: cheaper pickaxe or +5 mining speed
miner lvl 4: free pickaxe or +8 mining speed
miner lvl 8: steel pickaxe unlock or ability to mine fedoralite (yeah fuck you im locking fedoralite till you start grinding cause im running out of ideas)
note: researcher skill tree would be most affiliated to labs which its functionalities are classified to aegis so
researcher lvl 5: something something better lab stuff or the help gui shows how to utilize labs
researcher lvl 7: something something better lab stuff or help gui shows even more lab stuff
researcher lvl 10: something something better lab stuff or help gui shows almost everything you can do with labs
combatant lvl 1: +1.5% damage
combant lvl 3: non-gamer bunker guns become cheaper or +2% damage
combatant lvl 6: gamer bunker item prices are cut in half
these are just examples
doing this would enable the funny grinding neurons in the brains of 8 year olds which would increase retention time by a lot (source: 80% of roblox games)
i may be a dev but that doesent mean i choose what gets added, just because i say something here that might be stupid doesent mean it cant be subtracted from the original suggestion