I have to admit that I never played the original Doom much, most likely because I was still playing games on my Amiga back then, and not on the PC.
Doom The Roguelike is a rogue game set in the Doom universe. The game has been out for years, but has received a huge graphics update just a few days ago. Rogue-like games are named after Rogue, the first game of the genre that started the craze. They are basically dungeon crawling games with rpg elements.
In Doom The Roguelike you get to choose between three starting characters, the tough marine, the fast scout and the tinkering technician, and a starting trait. These traits makes you faster, do more damage or give you other advantages that you need to beat the game.
You start the game with one Experience point, full health, a weak six shoot pistol and no armor. You move around with the cursor keys or by clicking the mouse. The most important keys on the keyboard are f (or left-mouse button while hovering over enemies) for firing your currently equipped weapon, tab to toggle between enemies, i for your inventory and ? for game instructions and all controls. You can use the 1-0? keys to quickly switch between weapons, S to save the game when you are standing on stairs to the next level.
Saving is recommended as you will die in this game, especially if you are playing one of the harder difficulties. You always need to keep a good eye on your health and weapon to make sure you are well prepared for all the mean things the game throws at you.
Here is a 30 minute game instruction that should give you a pretty good understanding of game mechanics.
Doom The Roguelike is an incredible game, especially for gamers who like dungeon crawling types of games. Best of all? It is available for Windows, Mac and Linux systems.