For people going for the badge of the day "Master of One" badge, if your game lags horribly once you get to level 3 then just find one weapon you really like that does good damage (I went with the randomizer) and replay level 2 over and over again only using that one weapon. Guns get experience only by getting a kill with them so try to kill as many as you can with only 1 weapon
Here's a tip, equip ranged and titan units with the black sphere accessories when you can get them, they let your unit gain health anytime it does damage.
This game is crap and doesn't work at all, I start up a level and the screen just stays completely white until it takes me to a results screen, what the hell?
This game would be great if it didn't lag to the point that it's impossible to beat. Don't even bother upgrading the smash as you'll probably lag so badly that it'll fire long after you hit the space bar.