Are you a big fan of the old 16-bit Sonic games? Already sped through the first three re-released entries for the Xbox Live Arcade? You’re in luck: the final core entry in the original Sega Genesis series, Sonic & Knuckles, is now available to download for Xbox 360 owners for 400 Microsoft points ($5).

Not only do you get a full-fledged classic platformer, but if you’ve already downloaded the earlier titles — Sonic the Hedgehog, Sonic the Hedgehog 2, and Sonic the Hedgehog 3 — you can connect the games in a feature that emulates the Genesis version’s “lock-on technology.” Essentially, this means that you can use Knuckles the Echidna as a playable character in the levels of Sonic 2 and 3, and play a mini-game with him in the original Sonic the Hedgehog. Not a bad deal for five bucks.