More action and environmental storytelling:

• If you want to play more Portal, try community-made campaigns! I recommend in particular Portal: Revolution, a prequel to Portal 2 that features a few new mechanics, and Portal Stories: Mel, which has basically no new mechanics but turns up the difficulty by making you combine mechanics in clever ways.
• Bastion — Action RPG with a rich story and lush art. A humble narrator tells the story of a place literally torn apart by war, and you play the kid trying to rebuild. This was the debut game from Supergiant Games, which later made Hades.
• Tunic — Mysterious, exploration-focused adventure. A little guy in a green tunic picks up a sword and goes on an adventure, but the game is in an unknown language and you only have a few pages of the manual. It’s like a metroidvania but your progress is based on knowledge.

More “genre pushers”:

• Puzzle games
  • Mosa Lina — It calls itself “a hostile interpretation of the immersive sim”. It’s an aggressively random puzzle platformer where the levels are random and the tools you have to solve them are also random. Mosa Lina is a puzzle game that wants you to be clever, not smart.
  • Viewfinder — First-person “photography” puzzles. The featured mechanic has a “wow” factor that rivals Portal’s: Take a picture of the level, then hold up the photo and click to copy the photo back into the level. The plot is pretty meh, but like the original Portal, it’s pretty damn short.
  • Baba is You — Push blocks and break rules. Blocks with words written on them define the rules of the game: Baba is you, wall is stop, flag is win. The rules themselves are puzzle pieces. If you can’t solve the puzzle, change the rules!
• Inscryption — You find an old, abandoned video game and load it up. It’s an atmospheric, spooky card game, hiding layers of secrets for you to discover. The less you know before starting the game, the better your experience will be. You want one-of-a-kind experiences? This is one of them.
• The Stanley Parable — Comedy walking simulator. You enter a room with two doors in front of you. The narrator says, “Stanley entered the door on his left.” What will you do? The Stanley Parable has many endings and it questions what video game narratives are really for.