Some games ship with Orio built in. If a game you installed has an Orio UGC entry in its menu, you can change that game and play what other players made. The studio decides what may change - which numbers, which objects, which parts of the map - and you work inside those limits.
You describe a change in plain language, or use the in-game editors to tune values and edit the map by hand. Prompts draw from a daily allowance for each game - the studio picks the number, and it comes back the next day. Starting a mod by hand and tuning it costs no prompts.
When you sign in from a game, it shows a short code and opens webapp-ugc-445336701912.europe-west1.run.app in your browser. Sign in there with your Orio account, check the code on the page matches the one in the game, and approve it. The game itself never sees your password. If the browser tab did not open, go to webapp-ugc-445336701912.europe-west1.run.app/link/play and type the code from the game's screen.
A mod is one small file in the game's OrioMods folder - the in-game menu shows the exact path. The game reads it when it starts; the game's own files never change. Installing a community mod writes the same kind of file to the same folder, and deleting the file removes the mod.
Everything you make lands in your own copy of the game first. Prompt a change, play it, keep going until it feels right. Nothing you make is visible to anyone else until you submit it.
When your mod is ready, submit it from the game. The studio reviews it, and once approved it appears in that game's community list for everyone. Everything in that list is player-made content: made by players, reviewed by the studio, not made or endorsed by the studio.
A mod can only change what the studio declared moddable, within the limits the studio set — the game refuses a mod file that steps outside them, and games shipped with signature verification on also check every mod file's signature before applying anything. Every community mod has Report and Block: report anything that should not be there, or block a creator to stop seeing their mods. The studio can pause modding for its game at any time, and if your platform's parental or content settings restrict player-made content, the in-game menu follows them.
Redeem a code a studio gave you, and see every game you signed in to, on the Mods page of your account. Disconnecting a game there signs that copy out at once.