In a day and age where even laptops can have multiple monitors, like Mobile Pixels DUEX and TRIO Monitors (available on the Game Rant store in both dual and triple versions, with max sizes of both dual and triple monitors fitting up to 15.6" laptops), one has to wonder what that could mean for gaming. If a gamer recently took advantage of a Black Friday or Cyber Monday deal, the old monitor need not be thrown away but repurposed as a secondary or tertiary screen.
Not all games specifically support multiple monitors, so we can break it down into three main types: the games that specifically support multiple monitors, games that may require a bit of research or planning on another screen, and games that benefit from idle time. First-person shooters like Black Mesa, which finally finished development after 16 years, benefit most obviously from an increased field of view. In unpredictable game spaces where a threat could be coming from any direction, seeing more to either side always helps. Staring straight ahead, a gamer's field of view is 95° in either direction, meaning a typical 16:10 widescreen monitor covers, at best, a third of the potential field of view.
Many players have turned to search engines when they get stuck in a game, like those who were seeking all the hidden locations in Spider-Man: Miles Morales, so there is no shame in having a game's wiki open on a second screen. Some games fall short on the in-game documentation front end as well, so there is no shame in looking up secrets at that point.
There are also plenty of PC games out there where planning is essential for long-term success, especially city builders and other games where space is an issue. Survival games with scarce resources may benefit from having a calculator or spreadsheet open in another window to keep track of how much material the project will require, or the layout it should be built. While it is possible to recreate Legend of Zelda: Ocarina of Time in Minecraft by playing it by ear, it helps to have the schematics on hand in another window, rather than waste time correcting mistakes.
Finally, one should not discount the temptation to have a game open while doing something actually productive. Whether it's a puzzle or turn-based game that can be played in between emails, or an idle game like Blaseball, sometimes a game does well just sitting in the background, keeping the player company.
Check out the Mobile Pixels DUEX Pro Portable Dual Monitor.