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Red and green color contrast. I hate the cyan/magenta meme.
Forests or jungles.
Also perfect midair maneuverability like in SotN if it's a platformer or action.
Meaningful achievements. One of the worst example I know is Kingdom Rush, and I like the series. Or make them actually rewarding, like in Gemcraft.
Some room for perfectible scores per levels, if any. Not just 0-3 stars, but 5 or 10 (example : Incursion. it's a dumb Flash game, but, well, I like TDs).
A worthwhile single-player option. I have barely ever played a multiplayer-only game.
I prefer 2D and art to 3D.
Other things I love and there isn't a lot of : pre-rendered graphics, cinematic platformers (Inside, Limbo, Abe's Oddyssey...), point-and-clicks, mouse-based only game.
I like puzzles. Don't listen to puzzle haters.
A humane male hero. No Kratos/Duke """badass""".
More foreign mythology/folklore inspiration.
More generally, something designed by somebody. Don't leave it to random generation or chance, no "sandbox", no "open world", no "create your own game" or shit like that. Make it feel like you thought about your own game. This can even involve simple details, for example, reward exploration : if there's this really long path somewhere, or a small place hidden away and hard to reach, put something in it, an item, a chest or whatever. This makes it feel like the developer understands the player's mindset, and knows what it's like to want to explore everywhere, and thought about the moment that you would reach that place.
Also, I loved going back to old places in JRPGs when I was a kid, even way far back, just to see if I could. If you also make that rewarding that's even better, like somebody new appeared, or it changed, whatever.
Also big titties. And fanservice, but not stupid anime shit.
