I am still against any form of Tower Defense game because of a) the time taken and b) you can copy strategies from each other. And the original Tower Defense game also kinda caps at ~80, maybe ~90 at best if you figure out some new secret.
Also Cubefield is cheatable. Not that I think any of you would do that, but... :(
I still like Boxhead 2 but it takes as long if not longer than Tower Defense games.
These games from Orisinal are a lot of fun:
The Perilous Voyage