One game which falls easily into the low cost, addictive category is Orcs Must Die. Even keeping the name simple the idea was to stop a flow of enemies, orcs unsurprisingly, from reaching the end of the level using any means necessary to kill them. In Orcs Must Die 2 more orcs of all shapes and sizes must die and we have hundreds of ways to entertain ourselves in the process.



Link: HardwareHeaven.com