For me that would have to be Space Hulk: Vengeance of the Blood Angels. A hybrid 1st/3rd person shooter. Very strategic, methodic and somewhat slowpaced shooter, actually. Ridiculously difficult; imho. It was a game from EA that they put out on the 3DO. For it's time it had great graphics and, the atmosphere was pretty damn good too. VERY lively and realistic radio chatter from your "brothers" in your squadron. They actually had comments that were in line with what was happening in game, at the time. And the gore! Very nice. You'd know when/where there was a nasty fire fight. Lots of slop and...chunks, left behind. The enemies would constantly respawn. One single hit from their claws would wipe you out. Melee fighting was next to impossible, due to the strange lag in the controls, when face to face with an enemy. The levels got increasingly more complex and you'd literally play them for hours at a time, (no mid level save), just to set up lines of fire, only to have one of your brothers make a single mistake and have hordes of aliens come pouring down the hallway he was once guarding. That would amount to them coming up from behind the rest of your guys (the power armor being worn was very bulky and slow to turn) and the whole thing would just become a disaster area. There was one particular map that about broke my gaming ability. You had to, more or less, escort 2 of your boys that weren't armed with anything more than some flame throwers, which really weren't great for melee. So, you would take the rest of the team, which was about 10, and make forward lines of fire. Then you'd move out the 2 flamers behind them, then you'd try and make a retreating line of fire with the other five, then move this whole mess across a map with unlimited, respawning enemies, coming down hallways that sometimes had complex junctions where the slightest mistake would allow 1 single enemy to get behind one of your boys, and then you'd get to watch 2 or 3 hours worth of work disappear in a few minutes. The only way I beat this level was because the game "glitched out" and all the respawning enemies sort of just stood there. I took advantage of that, big time! Moved the whole team across the map and finally finished the damn thing...only to see that the next map was more complex. That's when I quit.