Not sure if this is already possible in VASSAL.
I have an operational game used to determine terrain for a battle (physical thing with real mapboard and blocks) in which each player has four blocks: one army, one scout and two dummies. Neither player knows which block of his opponent is the army or scout. It looks like this:
When you move a scout block into a square occupied by an opponent’s block you can ‘scout’ that block by placing your scout block above the opponent’s block. An arrangement of magnets means the scout block will detect the opponent’s army block by repulsion (so the opponent won’t know that his army has been spotted by the scout).
If an army block is placed over an opponent’s army block the two blocks are magnetically attracted to each other - snap! - so each player now knows where the other army is. In all other cases nothing happens.
Any way of doing something like this in VASSAL?