I wrote this guide a few weeks back. This is the best and only guide I know of for how to play Flash Element TD. People don't usually write guides for free online flash games, I guess it is not considered something that even needs done, so maybe it was silly of me to do so.... but I remember when I first found this game, I made a lot of silly mistakes, so taking the time to explain some basics of the game and also some pretty good tips would help a lot of people out! 

One thing that always caught me off guard is that the game seems to have so many options for air towers, even though there are so few air levels (~4-5). It'd make more sense to me if there were more air levels or even mixed levels with air and ground creeps. I mean there is at least one level that combines fast and immune creeps.......... it would have been a nice extra touch for the game, heh.

It's funny to me also, because when you first start, it seems like the game goes for so much longer but once you've gotten the hang of it, you just zip right through. Replay value doesn't seem very high to me.