RE gaiden was crap... a long time ago there was talk about a real port of RE1 to gbc, similar to that of aitd4.

"Q: Is there really a BioHazard (Resident Evil) for the NES, as I read in the "Did You Know..." feature?
A: Yes technically there has been a Resident Evil release for the NES, the thing is it is not an officially licensed Capcom game nor is it endorsed by Nintendo. It is actually a Chinese original pirate, which means it was developed and distributed illegally and also quite recently."

source: www.nesplayer.com/about/faq.htm

i guess this is sorta like the nes tekken2 game