Hello-
Can you tell a newbie if Vassal can support a game where the opposing players would not see or know where his opponents units are until they are within a certain range from each other, or perhaps within certain LOS parameters?

Given that no one has answered this, I’ll offer my opinion (based on ~12 months of module updating).

YES Vassal could support this kind of game, BUT… It would be a pain to code it and computationally intensive…

Every move would have to test EVERY piece of opponent A, against every piece of opponent B to determine the distance and then compare it to the LOS parameter to determine visibility.

This is a N-squared problem… If the game has 100 counters per side, then that’s 10,000 calculations/comparisons on every move…

As a followup, checking if 2 units are within range of each other isn’t too difficult (and you would really only need to check the just moved piece against all opposing pieces each move, so only 100 checks if each side has 100 pieces, not 10,000!), but checking for LOS (I’m assuming certain terrain can block LOS here) would probably require some custom Java code.