Slayers. It's old, but fun.

1: Interspecies Reviewers. So good, shame it was cancelled. 2: Delicious in Dungeon 3: I'm sure they're others

Death March to the Parallel Rhapsody. Stupid name, but it's my comfy pleasure. And no, it's not a harem, even though a cursory glance makes it look like it.

Konosuba is awesome.

Campfire Cooking In Another World With My Insane Skill: yes it's another one of those long-name anime, but it's a relaxing show about cooking and fantasy world travelling, nice vibes

1. Adapted from an RPG from our world:

• Pokémon Horizons

2. Set in an in-universe RPG:

• Bofuri
• Sword Art Online

3. Involved RPG mechanics:

• Cautious Hero
• Konosuba

4. Isekai-ed into an RPG (not sure whether to put in 2 or 3):

• Villainess Level 99

In no particular order:

• Sword Art Online S1 - It's hard to beat the terrific setup, the stakes, and conclusion for the Clannad arc.
• Shangri-La Frontier - The writer really captured gamers' mentality, and we even see the developers, yet the game itself still retains an air of mystery like a player experiences initially.
• Villainess Level 99 - Someone else who abused RPG mechanics, but a charming goofball for laughs.
• Solo Leveling - Power fantasy with RPG mechanics
• Log Horizon S1 - Competence porn for guilds

Danmachi has multiple RPG elements to it but a lot of rule breaking cheats to help the plot go forward. The lore/world building is expansive, most story arcs are good. It's better than it looks overall. And the OST is beautiful.

You'll have to make do with cheap animation, some fan-service (thankfully a lot less than the title would suggests), a pointless harem (MC is fixated on one girl and the story would fall apart if not) and plot armor.