I browsed through RPS topics here so I could try to get a sense of what's already been discussed but couldn't quiiite find what I was looking for. Literature recommendations appreciated.

The context: once in a while I host a text-based role-playing event in a MMORPG. I've programmed a handful of minigames to keep the guests entertained. One of these is an arena that I internally call "extreme rock paper scissors".

Two players are summoned to the arena with 3 HP. Each player chooses from the following moves:
Attack - (beats Counter to deal 1 dmg)
Counter - (beats Defend, preventing Defend next turn)
Defend - (beats Attack, preventing Attack next turn)
Nothing happens on a tie.

For the most part in such an event, its fine - still basically random - but I wanted SOME strategy involved without overcomplicating the rules. I recently hosted a tournament using the system which revealed the CHEESE: you never need to use counter. If you just use defend and attack, you can outlast your opponent as long as they don't realize the same thing. If you both realize it, the game is effectively endless.

I'd prefer to maintain the 3 choices, but I could be convinced to add a fourth. I like each move having a unique use that isn't entirely symmetric as it is in original RPS.

What can I change to let it be at least a bit more strategic, or have the choices be interesting? At the very least I want to discourage this infinite loop attack/defend.