Another game I owned on my Game Boy Advance SP growing up, instead I liked this one better. My friend had Doom (which I played) and I had this, which I thought was a little better. The reason is simple. It has less lag. The frame rate is improved and the maps are a little bit bigger. To start, the graphics in this game are similar to Doom, but the monsters and weapons look like they came from Quake (especially the Nail Gun). The engine was modified to run faster and have more dynamic lighting to the game. The sound in this game, is more the same from Doom, but the weapons sound a bit more futuristic, such as the pistol sound MORE like a laser than a gunpowder pistol. The game's music is just there, nothing much though. The game is still fun to play to this day, yet it still is more like Doom in the way that it looks with key cards and familiar-looking areas. The story is similar to Doom's but it takes place on an Island rather than on another planet. Where you are a kind of "Special Operations Unit" , trying to take down Genetically Modified Monsters that have been created by accident. The game has only about 20 levels, and password save, instead of battery save. The game is a bit hard which I will mention with some issues:

The issue with it being hard is quite obvious,  when you even play on normal difficulty, the monsters take LOTS OF BULLETS to kill. which is harder on the later stages. Speaking of stages, they are long and you can get lost if you are not careful, so try not to wander off too much or there will be backtracking, and lots of it. The most obvious problem that people have with it is that it is a "Doom Clone", meaning that it used Doom's game engine and made it into another game. Which for me, isn't necessarily a problem, as it was modified to run faster than the Game Boy Advance port of Doom.

To finish, if you find this game in a store, it is usually HALF the price of Doom, so if you can't by Doom for the Game Boy Advance (which is more than $20 usually) then get this. It may be kind of hard to find however, so don't go into average Retro Game Stores around your area and try to find this game. If you still want it and can't find it in your game store:

Just buy it off of E-bay or any other website online.