The Mega Man games have always been interesting and fun to play.  The ability to pick your own path through the game always makes the replay value go way up.  In the first Mega Man X game the creators at Capcom upped the anti by adding 4 armor upgrades, heart tanks and a revised subtank system.  What I took away from this game was how wonderful the play control is.  X is very responsive and with the ability to cling and slide down walls and springboard off gives the player a lot of freedom of movement not found in the old NES games.  I originally thought of the old NES Ninja Gaiden games when I first played it.  Mega Man X and Super Metroid probably have the best overall play control of any games on the SNES and should be included in everyone's gaming library.