It's technically not an alternate reality. It's the same world/reality, just covering different people. From the second movie, you saw that Jill had been in the mansion incident, and so we could roughly say the timeline was:
This block is around the same time:
RE:0 (game) Mansion (Rebecca, Billy)
RE:1 (game) Mansion (Chris, Jill)
RE1 (movie) Assumedly, another testing facility (Alice)
then:
RE:2 (game) Escape from Raccoon City (Leon, Claire)
RE:2 (movie) Escape from Raccoon City (Jill, Alice, Carlos)
and of course, then all the other games, as the third movie hasn't come out yet. I heard Leon will be in it.
It's technically continuous, just not intertwined.