I just realized I finished chapter 3 first, and now i finished chapter2...
no wonder I don't getting those achievement bonuses from the previous chapter!
Once you have the "miner " unit, just spam these baby's.
They give you an enormous energy boost. if you have the psysics lab also, they are accumulative, before you know it, the screen is filled with your units!
Ok I put 6 chansaws evenly spreaded, a bunch of turrets, mines and bouncers (no lasers), level 30 turtle spawn, and waited like 60 houres, still going! :)
the infinity wing option kills all the fun, that makes the game too easy.
otherwise, you can devellop this game even more!
going underground much deeper, or even into space :)
first of all, There must be a 4x or 6x speed button, to make the grinding a less painful experience.
Second you shouldn't charge money/crystals for recetting your stats.