Hidden and Dangerous 2. Squad based shooter set in WW2.
It's a fucking mess, barely hanging together but I can't stop trying to finish it because I can see what they were going for and I have a thing for old, overambitious games that bit more than they could chew, even if playing them drives me fucking insane.
When that game came out you already had super solid SWAT/Rainbow 6/Ghost Recon games, but the scale and feel of H&D was pretty unique.