Steam hardware surveys have shown that there's a lot of diversity in the displays people play their games on.
16:9 is considered a standard and the majority of Steam users have 16:9 screens in a variety of resolutions. However the number of people using alternative aspect ratios such as 21:9, 16:10, or 4:3 is nothing to sneeze at. There are a lot of reasons why somebody would use a non standard aspect ratio, but the point is that as game designers we have no control over the types of screens our games will be played on. So this presents and interesting choice.
- The designer can be absolutely sure of what will and won't be onscreen for every player at any time.
- Composition and framing are much easier.
- UI glitches will be less common. Problems like buttons overlapping each other or elements going offscreen will be easier to avoid if your menus are never put in an unexpected situation.
- It can be used for effect. Some games use an ultrawide aspect ratio for a "move-like" feel. Many games with a pixel artstyle use a square aspect ratio to make it feel traditional.
- Most players won't notice or care about black bars on their screen.
- Some players actually will notice and care about the black bars on their screen. People HATED this about The Evil Within and created mods that removed the bars. Other games that use letterboxing don't get as much flak as Evil Within did, but mods that remove black bars are still common for nearly every game that has them.
- If you're ambitious and want to port your game to lots of different platforms, a forced aspect ratio will make that a lot more difficult. Especially if you want to enter the world of mobile phones and portable consoles.
- The rigidity of a forced aspect ratio is something that some designers will disagree with.
Filling the screen
- A properly designed game can be played at any aspect ratio (to an extent), so there's no reason a game has to be one ratio over another when it can fill the whole screen. Most PC games I play will conform to both my 16:9 and 4:3 monitors with no differences in gameplay. A lot of games even offer you the choice of several very different aspect ratios and it never seems to affect gameplay at all in those games.
- Cropping can affect the difficulty of your game. 2D Sonic games are so much easier in widescreen that 4:3 feels like a handicap in comparison. In multiplayer games, players on a wider screen have a clear advantage over players with a narrower screen. Blizzard made a deliberate choice to force all Overwatch players to play at 16:9 no matter what monitor they're using.
- Some players who have ultrawide screens or multi monitor output might be able to see things you don't want them to see, which can break the illusion or even allow them to cheat.
So what do you think? In a general sense, is it acceptable to force an aspect ratio on the player if it gives you more control over the experience? Or should we design our games to work no matter what ratio is being used? This is something I've been wrestling with for a while now so I would love to hear the community's thoughts.