XSp.

Nice fighting game that came with those all in one NES cartridges.

One of the predecessors of modern 2D fighting games maybe, it was fairly simple.
I don’t remember the number exactly but you had to fight unarmed some 5 or 6 enemies equiped with different weapons (minus the last boss if I’m not mistaken).
Then, when you killed the last boss, the whole thing restarted with increased difficulty.
I remember almost completing 3 loops before dying… and I also remember there’s this technique of jumping bouncing on the wall that made killing most of them fairly easy… you just had to calculate the right distance for each one of them.
It also has a bonus stage were knifes and ninja stars comes flying at you… very difficult to pass.

Source: nesguide