Do you know of any game where you can actually use more than one monitor at once? Simulators might profit from doing so. Just imagine having a rear view or a radar view, or a damage control view... Maybe other types of games as well. Have you played any?

So you're talking about games that actually make good use of multiple monitor setups and not complete gimmicks like Darius?

Honest answer, beyond simulators, no.

It's too niche to get mainstream support (not that many people relative to the gaming population have two or more screens and a graphics card capable of pushing that many pixels around). Plus, it's not ideal having to keep glancing across to a second screen for additional information.

eve online , you have multiple accounts , more monitor easier to manage them

Racing games & flight simulators are the genres that usually benefit from specifically supporting triple monitor setups. Having said that, they do seem to be somewhat less popular recently with the advent of those huge 49" 32:9 Super Ultrawide displays (5120x1440 resolution) that show almost the same thing without any bezels. I did toy with 3x 24" 1080p monitors once when I had a couple of spare 24" monitors (was building a PC for a friend), and it worked OK. If I were buying new today though, I'd rather get a single 34" 21:9 Ultrawide for general gaming.

Supreme Commander on dual monitors setup. But I haven't played it like that, even though I use such setup. It seems that is not working on Windows 10.

side note - what about mutliple screens within a screen? Might I draw your attention to eXperience 112 aka The Experiment

https://store.steampowered.com/app/324770/eXperience_112/

I wish various strategy or simulation games would go multiple-window for their layout (so they could arbitrarily be set up by the user multi-monitor) rather than single window always being the only option. Some 3.1 and 9x (and MacOS < X) era games did this, and it certainly helps certain types of games.

If I did an sRPG/tactical RPG, I'd try to have one window be the "display", and other windows open to swap party info/skill selection independently.

Nintendo 3DS enters the chat...

DS (no "3" required) is a great example of how this can create helpful gameplay options. In the DS's case, each screen is tiny (both in size and resolution), and only one is touch... but it still brought good solutions. Wii U also had some games benefit from this (though sadly so me Wii U games [like that not-very-good Zelda game...] *forced* it and didn't let you go TV+controller only).

Eeeh, the DS sorta more a result of it's own limitations, most of what is done with the lower screen is down to the touchscreen, the asymmetrical screens would just be an overlay in other games.

Actually, any mmo games. It would be great to split your chat windows and such on two monitors. I bought one today (new), as a backup, since it's no longer in production. I'm afraid the price for a new console will be sky high pretty soon.

In strategy games, it would be nice to have one screen for managing locations, while the great picture stays in the other screen. For example:

Think a 4X game like Civilization / Pandora / etc or Masters of Orion / Stellaris / Endless Space / etc. It might be interesting to keep the overall world or galaxy map in one screen while we are managing a city or star system in the other. The "satellite" or "parchment" map of some games would look great in a secondary screen, also.

In games featuring real time tactical battles on large battlefields (in the vein of Total War, but not only) it would be great to be able to keep a view of the whole battlefield in one screen, while we are trying to focus on giving orders to units on a zoomed in screen.

In simulators like iWar or Silent Hunter II, where damage control plays an important role, it might help to keep said screen handy in combat (in order to know what you can do with your ship and, depending on the game, to actually assign priorities to damage control teams, like in iWar). Another screen that might be useful would be the navigation map while you are using the periscope: the officer viewing would ask and receive information viva voce from the rest of the team.

In adventure games and RPG it might help to keep a journal in the second screen. It might be an ingame map and journal, or it could be something that we are writing or drawing in another program (if you do not want to use pen and paper. This would be great. Exactly, strategy games would profit from this a lot. Windows 95 games like Civilization II took Windows seriously and allowed for a lot of freedom. Something in the same vein that allowed for fair use of extended desktop, would work. Also detecting screens and assigning them functions might be great as well. With a very large screen, like 34" or more, it might be interesting to be able to arrange information in different ways, in all kinds of games.

This is awesome, thanks for the input. Well, playing in a very large screen can be great (although not all games really look well at top resolution, and require going lower for them to be their own selves). However, even in that case an auxiliary screen might help. Although having the freedom to leave, say a 1900x1080 or 1900x1200 screen for the main course, then auxiliary windows like "overall map" or "rear view" or "damage control" that you could arrange at will would be great, if games were made providing that kind of freedom.

It is worth remembering how Stardock, for example, has made games with interfaces that adapt greatly to any resolution that you throw at them. That kind of care might be needed to allow people playing to adapt the interface to their possibilities. That would be great and useful. Much more than things like VR or the "Minority Report" interfaces that look like a tai-chi class on speed :-) Had to look for that one online. Apparently, the arcade cabinets used three monitors and the player saw their reflection in a mirror. The effect was that the three monitors appeared as one, seamlessly.

Who knows what people with time and room can do for themselves. But even having to live with borders between monitor and monitor, a secondary screen might be helpful for playing. In the thread there are examples of possible uses for either race simulators, flight simulators, other simulators (like ship and submarine simulators) but also strategy and even adventure and RPG, you name it.