I was just thinking today that it might be cool if they made a Luis survival horror side game. Think about it, we never see what he does when he's with Leon and Ashley, or what he did before they arrived. Judging from the notes that are left around, once he left Los Illuminados, he used alot of subterfuge, and did not attack directly. He really couldn't have since he only had that one pistol for a weapon. I think it would be cool if they made a survival horror game of Luis which took him from when he first fled Saddler's labs to when he is killed.
The game could feature you escaping the island and running through the tunnels that hsi grandfather taught him about. You would only have the pistol and maybe some flash bang grenades for weapons, and ammo would be very scarce (an exception would be made when you're fighting alongside Leon in the house). Tough villains like regenerator and garradors would impossible to kill, and you would have to choose wisely which ganados you would take on. Maybe in some areas, if you're spotted, an alarm will be sounded, and many ganados will arrive, thus forcing you to be sneaky. At the very end, there could be a boss fight, but one where you have to use strategy like in LiN. I think that this could seriously work.