There were two that were publicly shown, one is dubbed "fog" and shows Leon in a dark, spooky castle (specifically the home of Umbrella founder Spencer) and airship and the enemy is a cloud of living fog unleashed by the H.C.F. (this was later reused as Ouroboros in RE5), that was 2002.
The second was shown in 2003 and was the "Hookman" version, Leon is infected with something that makes him hallucinate seemingly supernatural things like a hookman ghost, living dolls etc, presumably the setting was still Spencer castle.
As a matter of fact, they DID do a spinoff with these ideas, the PS2 game Haunting Ground, although that was more based on the "fog" version and not the "hookman" one, judging from what we know about early RE4 and what wound up in Haunting Ground, Fiona and Hewie were actually in RE4 and judging from Haunting Ground, Spencer would have wanted her so he could be reborn as her baby (yikes)
I hope the RE4 remake reuses the "Spencer castle" scenario as certainly Capcom has got to realize people are getting sick of RE4 by now and since 2 and 3 remake can be seen as essentially their own continuity by this point, it's the perfect opportunity to do a "what if?" game, at the very least it'd be cool if they included that as an alternate scenario alongside a remake of the 2004 game, but that might be too ambitious, maybe as DLC?