Good game, the concept is pretty clever. I second the idea for a kill counter. It would add to player motivation. All in all, the controls are fine and I didn't run across any bugs, so good job :)
Bug: After pausing the game then resuming, the game freezes. Browser I'm using is google chrome. But anyhow, awesome game, very cute. If you're looking to improve it still, maybe you could make it a bit more challenging by introducing more variables into the gameplay with the blobs and the gems, or something.
After two generations or so, the Decimoid jitters up into the stratosphere and can't get back down again, causing it to time out. Not sure whether this is a bug or not, but it's a little frustrating. But I like the sound effects, very cute.
This is what happened to the guy in Give Up after he finally yields to Tass' psychological torture. Consumed with bitterness and regret, he becomes trapped by the thought of what he could have done, and spends the remainder of his life behind the cushioned white walls of an asylum.
The best way to get rid of groups of ninjas I've found is to have two or three burning temples (even better if they're on the long range thing). that way even though they disappear, they're still in range when the next one comes through, and they're destroyed really quickly. For ninja champions, the chilling crypt combined with the burning towers is pretty effective. and meteors, of course
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Thanks for the comment. Kill counter is available in Statistics screen but I could probably put it on game screen too.