okay i got the easy badge with just pellet towers i built as many as i could in a long curvy line the upgraded all of them then kept building lines and lines and upgrading and upgrading and my final score was 2111 Dude! You just completed the Dirty Desk achievement in Desktop Tower Defense 1.5 and won the Dirty Desk badge and 5 points!
Here's a tip though- First go around the perimeter and make sure no ends are pointing out. This is especially easy on corners, straight pieces, and three-way pieces. Than go around and connect something to every point on the four-way pieces. This provides a base to work everything else off of.