The UI is a bit cluttered graphically and there is a bit of grinding necessary at a couple points in the game but otherwise this was a ton of fun - a solid 3+ hours of gameplay.
Alien: So how are we going to attack?
Elder Alien: Just keep attacking them head-on.
3 days later...
Alien: We're running out of steam. Should we change our tactics? The rear and sides of the ship don't seem to be protected.
Elder Alien: Of course not! Keep attacking them head-on!
There's this exploit you can use in the Supermart (maybe some other levels, haven't gotten that far yet) where you can stand on the trash cans by the ladder and be unaccessible by the zombies...+ if you found this helpful. :P
The mouse pointer lags really badly for me so I have to use the arrow keys to scroll around the map, and I also have difficulty controlling my units, but otherwise, lots of fun and really addicting!
When I first started this game and I saw diamonds on the bottom of the inventory/shop windows, I thought that they would be virtually impossible to find (like in Minecraft). And then I went to the bottom layer...
 "Caribbean Admiral"){kind=icon}
 "Robot Wants Puppy"){kind=icon}
 "Kingdom Rush"){kind=icon}
 "Kingdom Rush Frontiers"){kind=icon}
 "Tyrant"){kind=icon}
 "Desert Moon"){kind=icon}
 "Days 2 Die"){kind=icon}
 "Necronator 2"){kind=icon}
 "Knightmare Tower"){kind=icon}
 "Burrito Bison"){kind=icon}
 "Utopian Mining"){kind=icon}
 "Nuclear Outrun"){kind=icon}
 "Dibbles: For The Greater Good"){kind=icon}