Vegetable Guy - Shoot both of the fruit stands in the center of market stage until both of the stands are destroyed
Game Breaker - Play as an engineer with the tesla coil kill streak and play on the base map. Put a tesla coil between the two jumping pads where the screen the armor games, sky9 games, or notdoppler logo is.
Party Time - In the first campaign level instead of going to hit the generator jump up from where you spawned and walk to the right. Fall down and jump across the gap where the disposal beam is. If you continue going right you'll unlock the achievement.
Hope this helps everyone!
The last level on Alien is nearly impossible. When you give someone 5X the HP do you really need to put a 4 minute time limit on top of that? It'd be more than a challenge without the limit but as it is right now is insane.