In the quest for a game that I could enjoy in-between watching my EVE Online sell/buy orders and doing work I came upon Defence Grid: The Awakening which so happened to be 50% off on Steam at the time of writing this.
As one can probably gleam from the title it’s a defence game more specificly a highly addictive Tower Defence game.
The premise is simple: to defend a group of power cores from aliens of varying types that run the gauntlet through your barrier of towers in waves, these waves get harder and more numerous as the game progresses.