As I was in the process of adding a game to the database, I was shown a list of fields into which I could enter URLs to that game's pages on various stores (Steam, GOG, Epic, etc.) but there was no URL field for the Microsoft Store. Why? The Microsoft Store has to be one of the most popular digital game sources. When IGDB adds a field for a Microsoft Store URL, I will edit the game's entry on IGDB to add a link to that game's Microsoft Store page.

When sorting an API request on e.g. totalratingcount descending, I'd expect the highest numbers to be at the start, and games with no ratings to be at the bottom. This is currently not the case, where games with no ratings (null) are at the start. This essentially makes the sorting function broken. Please treat null as zero in the API so that these games appear at the bottom of the response as expected.

Just like itch.io, there are lots of games are available on gamejolt.com. So, please add this feature where I can add Gamejolt link as a store. Thank you.

Be able to view the cover picture of a game title hovered in the search list when editing a custom list.

Be able to add URL links to home pages of subsidiaries and/or departments if they are distinct.

3D view of game covers, being able to view the front, sides and back sides.
Could be nice when having many regions and scanned images of all sides of a box art.

The Multiplayer Modes seem to have a theme when you look over the options available in Categorization. Almost all of them include specific special cases for some form of Co-op or shared Split-Screen, but none for LAN Competitive.

The most obvious examples I can think of would be the GBA Link cables for local LANs such as the Sonic games, or the Ad-hoc/WiFi features of the PSP, 3DS and others where these aren't Co-op modes or Split Screen, but Linked and Competitive.

Currently, custom lists seem to only show up on Desktop and fail to be listed on the mobile versions.
Is that something you can fix/add?

I want to send link to my Rated list, so that my friends would be able to see what games I like the most. It would be handy if it would be possible to send the link to the list, where everything is sorted from highest score to the lowest score. Currently, when I send the link, games are sorted by the date I rated them, no matter how I sort before copying the link

Currently, there are ratings displayed in "Rated" list (https://www.igdb.com/users/<username>/lists/rated). However, they are written in too small font. Originally I wanted to suggest to display ratings, because I didn't notice them at all. The main thing someone would go to this list is to see what ratings user gave to certain games. So, it would be better if those ratings were displayed in bigger font and maybe not in grey color.

A rating breakdown for your own scores, it could be the same rating breakdown as seen on game pages.

Get an email whenever a game you want is released or the release date changes.

For games and platforms there could be an icon imagem, of small size, which could be used as a visualization flair on the website and also as a data point for the API, as applications could use them to their UIs.

Game revisions (like Alpha, Beta,1.0,1.1,1.2,2.0, etc) would be good for reviews, because the game can change since someone reviewed the game. Even old games have revision (Rev 1, Rev 2, like in the No-Intro notation). It is not a particularly needed data point, but some games change a lot with time.

https://www.igdb.com/games/rainy-season

Can't receive updated data for this game through the API.

As means of promoting game editing, there could be a game recommendation for the user. It would be based on the game pages the user visited, the games the user rated, etc. A notification could appear on the website with the recommendation, and there could be a place in "Karma hunters" for some more recommendations.
It would certainly help with many more game info missing, as the person would be prompted to help with something they most probably know.