Metal Slug 3 | Steam | £2.99 (save £3)
Metal Slug 3 is an absolute gem of a game, and arguably the best of a classic series. Not just because it has rideable ostriches. Great bosses, intense action and a hilarious sense of humour means this old-school run & gun SHMUP can still hold its own. Better yet, you can save £3 on it. Thanks to theg @ HUKD!
NB: Metal Slug 3 isn't compatible with Windows XP, in case you still run it.