If you want a good Vietnam board game, try out Vietnam 1965-1975.
It is a hex based game, using counters for playing pieces. The game is from the 80’s and you’ll find it on Ebay.
For sure, no game depicts the vietnam war better - with hidden units, ho chi minh infiltration routes.
Beware though, that the Grand Campaign 65-75 takes hundreds and hundreds of hours to play. However, there exist about a dozen smaller scenarios (like the Tet offensive amongst others).