The Door Problem of Combat Design
The fundamental problem is "player benefits from minimizing risk", which is usually boring. It happens in most genres, e.g. it's especially bad in roguelikes, where luring enemies to doors is a common tactic.Of the proposed solutions: cover, hidden information, and enemy leashing are only obfuscating the low-risk path, not actually removing it. A good player is still rewarded for boring play, e.g. bouncing grenades at the leashed enemies.Rewarding risk-taking is a good solution, but hard to implement in a FPS because there are only so many rewards you can give.One-way paths are criticized for breaking exploration, but I think it's possible to get the benefits of them while still allowing exploration. Consider Ninja Gaiden for the NES. It spawns enemies when you cross certain thresholds, and crucially it does this every time you cross them, even if you already defeated the enemies. This punishes retreat by undoing any progress you made. You're forced to take risks, and it's IMO a better game because of it.Some people call Ninja Gaiden unfair, but I think that's because they didn't understand the mechanic. You could get the same benefits while making it easier to understand, and more fair feeling, e.g.:* Clearly mark the spawn triggers* Visually show the triggers activating, e.g. with particle effects flying from them to the enemy spawn points* Don't let the enemies harm the player immediately after spawning, so the player has time to react.* Cap the number of active enemies and the spawn rate from each spawn trigger (Ninja Gaiden has sprite limits, but you can still produce absurd-looking spawn patterns by repeatedly crossing the trigger point).Ninja Gaiden also has time limits, which are IMO an underrated method of punishing boring play. Time limits aren't fashionable in modern games, but I think they should be brought back. They're compatible with exploration by including hidden bonus time powerups.