One feature I enjoy in Slay the Spire and Spirit Island is that both games have highly customizable difficulty, both in type and degree. This lets you pick how difficult (or easy) you want your game to be.
Slay the Spire has its base game and then Ascension. There are 20 levels of Ascension, each of which dials up the difficulty a little more, usually by adjusting a number or two. About half the levels are increasing the damage, health, and movesets of normal, elite, and boss enemies.
Slay the Spire also has custom runs, which let you pick one or many modifiers to the game. Want more control over your starting hand? Here are several options. Want more randomness? More options. Harder fights, easier fights, trading off one thing for another? Screens of options. Or try the daily mode for a random set.
Slay the Spire also supports mods now, so you can adjust the game to the limits of your competence.
Spirit Island has its base game and then adversaries. You can decide that your invaders come from one of four European nations, each of which has base modifiers and then levels 1-6 of increased difficulty. The “base” difficulty of each nation varies, so the game comes with a chart showing how each adversary & level ranks on a scale of 1-10. (They considered having the “levels” just be the difficulty level, but it caused more confusion trying to explain why the numbers might be “1, 2, 4, 6, 7, 9, 10,” and then people referred to the top level as “six” anyway.) The next expansion adds more adversaries and a way to combine them for stacking difficulty. And then there are two levels of lowered difficulty (which can stack). (I should try dialing difficulty all the way up and all the way down at once.)
Spirit Island also has scenarios, which let you pick a set of modifiers to the game. Most of these make the game more difficult. All of them make the game different. One makes everything faster, one focuses on guarding the island’s center and another the island’s coast, and another adds a chance for random buffs to the spirits or invaders. Several add and remove win and loss conditions. I am particularly fond of one named “Second Wave” that lets you keep the same island after completing a game, reset some variables, then keep playing with new spirits.
Sometimes you want to try new things. Sometimes you want to challenge your limits. Sometimes you want to faceroll.