There is a new version of Desktop Tower Defense out (V1.2). To quote the news page,
1.2 finally released! And a new front page, which sucks a little bit less than the old one. The update contains all new quicker pathing, a new creep type, a new tower type, a new creep distribution, more challenge modes, a new fun section and lots of small fixes. The towers have been rebalanced slightly to make way for the bash tower. Older versions will no longer be able to submit scores. I am also in the process of upgrading the server which all your donations have allowed me to afford. Thanks!
I do believe I saw a creep squeeze between two diagonally aligned towers!