Chess has absolutely no core loop.  The closest thing it has is that little meta-rule where you can't take your hand off a piece unless you want your move to be official.  Or the turn timer.

Chess is about tactics and possibly a small amount of strategy.  The strategy is something like: "I'm going to get my knights out and fork some things".  The tactics is the actual process of moving pieces around the board.  Making trades.  Attacking.  Defending.

The whole game is about "moving uphill" during your turn while limiting the amount of hill your opponent can climb, knowing that they are doing the same.  Where moving uphil means to move towards winning the game.  Given that the game is entierly tactical, it is also largely predictable.  Despite the enormous branching factor of how many moves each player can make, there is almost always one move (in the mid-late game) which is the best, and therefore predictable.