Pythagoras: the rules are very difficult to implement. Even if it seems quite easy for check-check-check-check with the same piece, it will be much more difficult to understand for chasing. If you attack a protected piece of the same value, than it is no more chasing. If you chase than chess than chase it is -apparently- legal. So quite a nightmare to implement (and to understand). I guess a way to "request draw" is probably the best, because most of the situations can be quickly judged by Fencer.