This looks to be the exact case with protagonist Tom's bessie mate Harry, with one key exception. He's a sadistic and powerful cyberdemon inhabiting the depths of Hell. As Tom, the player must prepare everything for the party and ensure nothing goes wrong.
I always like to start a game's review with its most praiseworthy feature. It sets a good precident and doesn't put potential players off. And by far the best feature is the humour! The game's witty narrative and dialogue had myself and no doubt many other players in stitches. The ending in particular made me laugh out loud.
The game is created using the sprites from classic shooter Doom, and in many ways its main audience is the fans of the game. There are many tongue-in-cheek references packed into the game (including the shocking truth behind why there is body armour and other human-friendly assistance in the depths of hell) and playing will give the golden oldies of video gaming good things to reminisce about. It's almost like Doom was a film (I refuse to acknowledge the existence of that one with the Rock) and this game is a massive DVD extra released for the remastered edition.
Beyond that, it's a wonderfully intricate game. It verges on the easy side, but being needlessly complex would ruin the fun appeal. The comparative length (it took me roughly half an hour to complete) leaves the player wanting more - this is a praise rather than a criticism.
All in all, Harry's 21st Birthday is incredibly inventive, brilliantly original and works as a fine tribute to a classic game as well as shining in its own right. It's funny, punchy and seamless.
Final Score: 8/10