What a fair difficulty curve actually looks like

There's a clear difference between a game that gets harder and a game that gets more tedious. The first teaches you a new idea with every spike in difficulty. The second just inflates enemy numbers and hopes you don't notice.

A fair curve introduces a mechanic, lets you practice it in a low-stakes fight, then tests it when the pressure is on. When I lose to that kind of challenge, I usually know exactly what I did wrong.

The warning sign is when the only solution to a tough wave is to go back and grind resources. That's not difficulty, that's a stall. Great strategy games want you to think your way out, not farm your way out.

When you're evaluating a new game, pay attention to your first real defeat. If it made you want to try again immediately, that's a good sign the designers know what they're doing.