Unfortunately, being able to place the blocks anywhere you can see is a bit of a game break if you have more than one, because you can literally just go up and around most obstacles if you have even a small amount of room.
Level 11 is evil. Pretty much the only way to win it is to armor up seven bots and then immediately rush the enemy and forcibly take up it's territory and spawn new bots ASAP.
If you get stuck fairly early on in the game, just build two generators, a bunch of fighter bays and set them to Interceptors. It keeps most of the heat off the structures and the base, allowing you to build other larger things.
The controls for this are very clunky. Because the pixels auto attack anything that comes nearby it becomes almost impossible to maneuver in a way that lets you win.
The best possible virus you can make consists entirely of "jacK". Each one boosts your stats by two points, and you can get more than one if you beat the lower left "Metazoa (Live)" test, exit the page, beat any level to get the "You won" letter then continue to beat that level until you have as many "jacL" as you have rows in the Sequencer.
Turns out that maxing out Defense and Reproduction is EXTREMELY EFFECTIVE if you use the Reproduction enhancement to outnumber the other viruses by sheer number, while you let the defense do it's work.
 "Color Theory"){kind=icon}
 "Minimalizer"){kind=icon}
 "Tentacle Wars. The Purple Menace"){kind=icon}
 "Upgrade Your Enemy"){kind=icon}
 "Clockwork"){kind=icon}
 "Nano War 2"){kind=icon}
 "Hackey: the Hackening"){kind=icon}
 "Adapt or Die"){kind=icon}
 "Obliterate Everything 2"){kind=icon}
 "Pixel Legions"){kind=icon}
 "Geek Mind"){kind=icon}
 "Phage Wars 2"){kind=icon}
 "Bureau of Steam Engineering"){kind=icon}
 "Gravitee Wars"){kind=icon}
 "Transformice"){kind=icon}
 "Zening"){kind=icon}
 "Evenator"){kind=icon}
 "The Codex of Alchemical Engineering"){kind=icon}