Battleship Chess

I had an idea where each player, before the start of the game, would choose three (the number could be increased or decreased) pieces, pawns, or a combination of the two. For example, two rooks and one pawn, or three pawns, or two bishops and a knight, etc. However, players cannot choose their king. Each player chooses the pieces/pawns among their respective color (the white player chooses white pieces/pawns, the black player chooses black pieces/pawns). The selected pieces are called battleships. Once selected, the game starts and behaves like normal chess, but if your opponent captures all your battleships, you lose the game. Your opponent does not know the pieces you have chosen, and vice versa. However, when a battleship is captured, the information is revealed. So, if my opponent captured a pawn, which was among my three battleships, I would announce to my opponent that they had captured/sunk one of my battleships. Capturing all three battleships an opponent controls wins the game, but so does checkmate. You could ignore searching for your opponent's battleships and hunt their king, or you could hunt for their battleships and ignore their king. The game can also be played where battleships are not revealed after one is captured (this is the way I prefer.)

Online versus over-the-board

Playing this variant over the board would require players to write their selected battleships on paper before starting the game to avoid cheating. 
If an online version were created, having a player's three battleships highlighted or colored differently could be a helpful reminder to keep them safe (the highlight/color variation would not show for the opponent).

The variant idea reminded me of a more dynamic version of battleship, hence the name Battleship Chess. Let me know if you need anything clarified or want to discuss this variant. I am aware that there are many chess variants in existence, so if one has already explored this idea, please let me know.