Widescreen

Widescreen designates screen aspect ratio wider than 4:3. Typical widescreen ratios are 16:9 and 16:10, though even wider ratios such as 21:9 are starting to appear.

The Doom engine's original resolution of 320x200 corresponds to a logical 16:10 aspect ratio, however it was not intended to for widescreen displays, but to be stretched vertically into the equivalent of 320x240. For this reason, a "lazy" way to support widescreen resolutions is to simply withhold aspect ratio correction, resulting in a squashed image. Proper widescreen support requires instead rendering additional areas on the side (effectively increasing the player's field of vision), but runs into the problem that many graphics, such as the title screen or the status bar, are only 320-texel wide.

Source ports support
Official ports that support widescreen:
 * Doom Classic Unity port since the September 3, 2020 update. The IWADs and several of the official add-ons have been updated with 16:9 graphics in 426x200 resolution, namely both parts of Final Doom, No Rest for the Living, Double Impact, no End in Sight, and Deathless.
 * Doom 64 (2020 version)
 * Strife: Veteran Edition

Third party source ports that allow widescreen resolutions include:
 * Crispy Doom
 * DelphiDoom
 * Doom Retro
 * Doomsday Engine
 * Eternity Engine
 * GZDoom
 * PrBoom+
 * ZDoom