AI War: All Of It | GamersGate | £2.70 (RRP: £12.99)
If you're spoiling for some incredibly tough space strategy action with the scale of an old-school 4X title, AI War is pretty much your dream game. Arcen Games delivered an absolute corker that has massively grown over the last few years with numerous DLC packs and sweeping expansions. It can all be yours for £2.70 from GamersGate, who'll also flog you the DLC separately at a massive discount if you already bought it in a bundle.
Be advised, though, I'm not kidding about AI War being hard. In fact, I didn't feel capable of reviewing it, because I sucked so badly at it.