It's not often that a game receives online multiplayer years after release, but it does happen. Case in point: Double Dragon IV from Arc System Works. The retro-style beat 'em up came to all major platforms, one system at a time, but initially without an online mode. A few years later, though, the game was updated to add 2-player online co-op! That's quite an addition for a small-scale $7 game, so we had to try it out and share our impressions.