Case Zero has you play in a town for the main character from Dead Rising 2, Chuck. Without giving too much away you have to "build" your way out while at the same time ve your daughter Zombrex in order to prevent her from going full on zombie. The town is a decent size and the game can last you any where from 3-8+ hours depending if you want to do everything.
Case West has you play with Frank and Chuck in a factory. I haven't bought it but from what I recall it does take place after DR2. The factory is a bit bigger if not the same size as the town in Case Zero. It also has CO-OP.
Both are well worth it. In your case buy CZ, then find DR2 for SUPER cheap and play it.
Question- DR2:OTR takes place in a different story line or after DR2. I've been meanign to buy the game for the longest, but with this damn backlog I haven't yet.
Yep. Another thing to mention about Case Zero is that you can build a few levels on Chuck and import that into DR2, giving you a little head start. The city is open roam, maybe the size of a sub-section of the mall (for reference to DR1 for those who haven't played beyond).
Case West builds off one of the endings. Staying spoiler free, don't worry. Both DR games have "S" endings where if you meet certain story conditions, there is an extra bit of story/game (called "Overtime Mode"). In DR1, this is the general "canon" ending, and at first appeared to be for DR2 as well. But Case West build from the "A" ending, bringing together the protagonists from both games. They team up in Case West and the story builds towards making DR3, so right now that is considered the canon story.
DR2: Off the record is a "what if?" type of story. In it, Frank takes a different path post DR1 and ends up as the main playable character of DR2. Haven't done that one either, but I do know it's a completely different non-canon story. Basically made due to the fan reaction/backlash of wanting to continue playing as Frank in DR2. People didn't dislike Chuck, but Frank's popularity just soared (thus him being in things like MvC3) so they were surprised that the sequel had a new character.
If anyone is interested in co-op for DR2 or DR:CW, send me a message on XBL.