Nebula official Web page
NEBULA is an emulator for the hardware found in the CAPCOM CPS2 boards. The games that use this hardware include Super Street Fighter, Street Fighter (Alpha, Zero, Alpha 2, etc), games with Marvel characters and Dungeons & Dragons series.
In order to play these games, you'll need the ROM images of the board and also a decryption table for these ROMs. You'll not find any ROM links in this page. You'll only find links to the decryption tables for these games.
NEBULA is free and can be freely distributed as long as it is not packaged along with ROMs.