Good game, just wish it was a little harder early on so the last level wouldnt seem so hard. Beat lvl 17 on first try. Beat lvl 18 on 1st try after I got Elf Race maxed out. Pretty easy to get hard badges, just takes a long time!
Made it to Wave 605 in sandbox mode...Probably would have made it a little bit longer if I had not got bored and walked away from the computer...ah well...still impressive.