Here I'm going to talk about one of the main ways to bore your player if you're making an action game (or really any kind of game, but it's especially relevant to action games). This is having significant periods of time where the player has no control. If you're writing an action game combat system, the player should always have control of their character; any second they don't is a second that they're not playing, and consequently, a second where they're not having fun. This mistake can be seen in any game with combos that can't be escaped once you've been hit by the first strike, or enemies that grab you and leave you helpless for several seconds while you slowly take damage (I'm looking at you Dark Souls). Dragon Ball FigherZ is by far the worst offender I've ever seen. In that game it's not uncommon to be left watching your opponent play a singleplayer game for ten seconds or more, and there are even ways to kill someone from full health without giving them any input after your first hit lands. It actually killed the game for me.

Now you may think I'm being a little unreasonable advocating for the complete removal of "true combos" from all games. But just what purpose do they serve, exactly? If you can't escape the combo, why isn't it just one attack? In a game like DBFZ, it's a little more defensible because it takes real skill to continue the combo, but in games where it doesn't, I really don't see the draw, and I've already made the downside clear. I want to see a game where I never have to stop playing unless the game is loading (still undesirable but inevitable to some extent), or it's time for me to go do work...