Games

I taught my wife to use WASD+mouse on Final Fantasy XV. Nice and beginner-friendly in the beginning.

My wife is really into the sims and oddly enough 'House Flipper was a really goof intro to wasd co trols in something she was interested in. She can play most anything these days.

I learned how to play with keyboard and mouse with World of Warcraft. Current retail WoW is terrible in my opinion but plenty of good private servers exist. Turtle WoW is great. MMOs do use more than just the basic wasd keys, but aside from those and the 1-0 keys, there is no rush to mash keys quickly. The rest of the keyboard is basically just hot keys to open up windows and menus. It helped me learn to be versatile with keyboard/mouse without being punishing when starting out.

Have a look at Razbuten’s “non-gamer” playlist on YouTube. He makes some interesting observations. Several of the games being suggested here are also used there, and prove more difficult than some would expect.

minecraft

Some particular reasons why I’d recommend Minecraft for this:

• it’s very easy to get started, but there’s a lot of depth if you get into it
• its pretty slow-paced
• its a multiplayer game where someone of a much higher skill level and someone of a much lower skill level can play together without the noob player feeling that they are holding the advanced player back
• if you set the difficulty to peaceful it’s hard to die, and it’s impossible to fully “lose”. You can also turn on keepinventory.
• it’s a very open-ended game where you can come up with your own goals, which makes it something that everybody can find fun in their own way
• if they do get into it, it’s a good segue into a wide variety of other games. Just figure out what part of Minecraft they enjoy. You can also extend Minecraft by playing with mods.

Stardew Valley.

It's 2D, co-op, not difficult or punishing, has few inputs, and is approachable mechanically.

The various valve games would probably be ideal.

Portal 2's co-op mode perhaps.

Fortnite's Lego mode would probably work very well. Since it's targeted towards younger kids that are still learning how games work.

Serious Sam franchise would be fun too.

I used to always use Minecrat for this. Sure, they can't do everything immediately, but I put the game on peaceful and let them explore at their own pace.

I say "used to" because Luanti (formerly MineTest, an open source Minecraft Clone*) is finished and free.

(Okay, Luanti is a lot more than a Minecraft clone. But for this discussion that's all one needs to know.)

Portal maybe

Is she familiar with Animal Crossing? If so check out Dinkum. Other suggestions: Terraria, Core Keeper, Minecraft, and there is always classic FPS games lol. I learned WSAD in Quake

Minetest.

My SO went from learning the controller with Fall Guys to Minecraft WASD. I think Fall Guys is was close to perfect, low amount of inputs, high amount of engagement.

...any of the traditional action platformers.

Portal, Spyro etc.

I'd go down the route of so called 'Walking Simulators'* though I use the term First Person Experiances, such as Dear Esther, Gone Home or maybe even Firewatch. Games were you can take you time and practice the feeling of movement. From there if you are looking to get into shooter style games go for something Co-Op. My wife and I started on Time-Splitters where she basically stayed back as a sniper whilst I ran in. (This was back in 98/99) From there we ended up going through Halo, Gears and eventually Borderlands as they came out. Anything where you have a bleed out / respawn mechanic is great.

*For me a walking simulator would be more like Octodad where you actually have to work at the walking! :D

Minecraft.

There is Portal: Flash, a browser-based Flash game, if you can run it. Tons of fun. Also Minecraft (BUT maybe use version 1.13 or earlier in order to cut out some harassment, Illagers and raids might deter new players. Mainly they just piss me off. Go 1.12 or earlier to avoid Drowned and Ocean Monuments/Guardians) and The Room 1-4

Terraria on Journey or Classic mode fits all of those

Slime Rancher would probably be a good introduction to fps controls.

phasmophobia

Blue Prince just came out a week ish ago and it's fantastic. It's a puzzle/clue game with lore and a charming aesthetic. Controls are simple, wasd and left click and sometimes E. It's addictive, but can be a slow burn if you don't get engaged right away.

GTA/RDR? Shooter where you're not pressured to do much, explore at your own pace, shooting but without the "stress" of doom or something similar. And no need for quick aiming or whatever. Pretty chill game to learn controls in, imo.

Son wanted to play Minecraft, here's your mouse and keyboard

I'd consider what kind of game she finds fun and compelling--that's more likely to engage her to become familiar with the mouse/keyboard combo.

That being said, Minecraft on peaceful mode would fit and is generally approachable. Stardew Valley is pretty relaxed as well, though I don't remember whether it uses WASD specifically.

Maybe Valheim? You could turn the settings to peaceful mode if you don't want to deal with combat quite yet - although combat at the beginning isn't super in-depth - but it doesn't have a ton of buttons and the start of the game is a lot of basic "walk around and find things to interact with."

Modded Skyrim (to make is very easy, or even invincible). How best to learn to move in a 3D world than by giving them the best game world to discover.

I always use controller but I recently played Oxenfree and it was much easier with keyboard and mouse.

Are not difficult or punishing

Oh. So, not Noita...

Minecraft

2D: Survivors/Bullet Heaven type games. Most are WASD to move, mouse to aim (if at all).

3D: Vampire Hunters. Since it auto shoots the focus is on movement: strafing, aiming, and avoiding getting hit by mobs. Dying early is expected, so no pressure on getting a perfect run.

Firewatch

Halo CE

Pineapple on Pizza is a short one shot game, it's cutesy with a twisted ending. Uses WASD and Mouse

This might sound weird but the first game that came to my mind was cod. If the goal is only to familiarize her with the controls then you don't even need to play online. Just load up in a private lobby alone and learn how to walk while looking around, add in sprinting and jumping, then figure out how to aim and shoot at stuff (stationary if necessary). I imagine that if she's able to get comfortable with all that then she'll be fine with literally anything else.

Other than that just play games that you're both interested in and the controls will come with it