the secret to multitask is to get a mortar really fast in the top right, build 2 mortars only in the bottom right, build 2 mortars in the bottom left and build one mortar in the top right in the third or fourth row. after that, reactors and speed will get you ready to make your move.
 "Pandemic 2"){kind=icon}
 "Shattered Colony: The Survivors"){kind=icon}
 "Creeper World: Evermore"){kind=icon}
 "Creeper World: User Space"){kind=icon}