Hey, this is the perfect topic for me. I'm playing Silent Hill for the PS1-replays right now, but will definitely consider joining here as well when I'm done with that. As for games I havent played yet there are of course a ton, but I think I will go with these:
Teenage Mutant Ninja Turtles - yes the infamous original. I think the difficulty of the water level in this game is waaaay overblown, but the game gets pretty tough later on, and I've never finished it. Time to put that to rest.
Metal Gear - I own both the MSX-version (on subsistence) and the Nes-version, but I think I might cheat and go with the MSX-version - at least first.
Bionic Commando - I havent played this much, but I cant get anywhere in it. Not being able to jump is just so weird. Guess I just need some practice (and maybe a code for infinite lives or something if that exist).
Ok, a fourth one if Metal Gear on the MSX doesnt quite fit, would be the original Adventure of Lolo that i've not only never completed but never played. Got a copy last year that is dying to be played! I also have Batman an Return of the Joker unbeaten, but I'm not sure if I will ever be able to remedy that
I would also love to play the following games that I own:
Crystallis - have the NTSC-version, but right now only a PAL-Nes so the speed will be bad. Waiting for my NTSC-toploader to get a mod I think.
Final Fantasy III - or rather the DS-remake. I count this still, since the original was for the NES.
Dragon Warrior III and IV - well for the GBC and DS
Willow - same as with Crystallis, I own the NTSC-version, but would play with wrong speed on Pal-Nes
Ninja Gaiden II - same as above
Star Tropics 2 - same as above
Kid Icarus - same as above
Robin Hood: Prince of Thieves - same as above
And this reminds me that I still havent beaten that last boss in Rygar - guess that is the game to start with if I ever do this