The old 2003 game 'Vietcong' is still, IMHO, the most realistic depiction of jungle combat conditions in the Vietnam war (at least, in a singleplayer game). It can oftentimes be a janky, overly hard game, but there's still nothing else quite like it all these years later.

The jungle is dense for that period, the AI is surprisingly tactically aware (at least from memory. They would ambush you, flank the player, and I think even run away if they were losing an engagement), there's deadly, well camouflaged traps everywhere, making slowly walking the safest way to move around, the fights are short and deadly, and most impressive of all, it licensed a lot of famous 60's songs from that era.

It can be a difficult game to get running on modern windows, but there might be some community patches for that. It would probably run better under Linux with wine.

If you're looking for a hardcore singleplayer experience to explore that conflict from a historical context, I'd recommend giving it a shot.

Lost Patrol for the Amiga

Battlefield Vietnam

I know it's old and an EA title but it has the best soundtrack outside of 1942 menu music.

I'm with ya on rising storm 2. It's just a shame what TWI has done to the game since the EGS update

Vietnam servers in Arma reforger.