100 Things You Never Knew About Resident Evil
32. Boom Goes The Dynamite
Grenades have long been a part of Resident Evil, even if it was originally just as an ammunition type thanks to various Grenade Launcher weapons (or, in the first game, the bazooka). In terms of actual hand grenades, players didn't get to try out small explosives until RE4.
That said, there were at least two prior attempts to integrate throwables like this into the series.
One of the many cut ideas from Resident Evil 2's "1.5" days, grenades were found in the code of the leaked build of the game which tracks with RE2's increased focus on action. They were also somewhat functional at this point in development too, as Leon has an animation for rolling one across the ground and they provide a small explosion. They're also one of very few Resident Evil weapons which can actively harm the player if you stand too close.
Whilst they never made the final game, Capcom tried again with RE Zero. Yet again hidden in the files of the Trial Edition of the game, modders found an icon for a red hand grenade. However, they do nothing whatsoever and this icon is missing from the final release.