A good difficulty curve is a kind of storytelling

The best strategy games never stop teaching, and they rarely do it with text. A well-built difficulty curve introduces one new threat per level, lets you fail, and trusts you to work out the counter.

Casinacho Games does this quietly. It adds branching lanes before armour, armour before rerouting bosses, so by the time everything stacks up you already have the tools. You learn by playing, not reading.

Bad curves either dump all the mechanics at once or coast for twenty levels before any challenge. Both lose players. The sweet spot is a steady drip of new ideas with just enough room to practise each one.

When I review a game's pacing, I ask whether I understood a new enemy before I was punished by it. If the answer is yes, the designers earned my trust. If not, I usually quit around the fifteenth level.