This version included a number of features in addition to those found in the Doom 0.4 alpha version:
- Collision detection between objects; it is possible to walk into monsters and pick up items.
- It is possible to shoot monsters. However, there is still no animation at this stage, and when monsters are shot, they simply vanish. Although certain enemies (like the Demon) have beta death animations.
- A working status bar and the ability to change the screen size.
- A working menu.
- Working platforms.
- An Automap.
- Skill levels. The easiest is "I just want to kill", rather than the release version's "I'm too young to die".
- The rifle's sprite has changed, though the bayonet uses the same sprite.
- The rocket launcher can be picked up and fired, but it does no damage. It reuses the sprites of the shotgun.
- A non-functional command line argument to record demos ("RECORD <mapname> <demoname>"). Launching the game with it causes the game to get stuck, displaying only a blank screen.
- Animated floor tiles (in addition to the liquid animations)
- Keys —or passcards— for locked doors; as a partial carry over from Wolfenstein 3D initially (and internally) designated Bronze, Silver and Gold, later changed to Blue, Red and Yellow.
After the player quits the game, the ENDOOM screen states that it is a preview of Doom: Evil Unleashed.
Version 0.5 included several levels, most of which were modified and used in the release version of Doom. Level 6 was held back for Doom II. Unlike the previous alpha versions, Doom 0.5 is open ended and unlinear; the player can transition between levels at will. This is also the last Doom version with Tom Hall aboard the development team, so these map versions are the most recent to reflect the vision laid out in the Doom Bible. The levels made by Hall are mostly identical to retail, with the notable exception of texturing, contradicting developer John Romero's statement "most of [Tom Hall's] levels had very little work done to them, in fact".
All the playable levels are internally designated E1Mx, where x is any number between 1 and 13. This still reflects the original intention to have a full 13 levels for episode 1.
As a final technical note, an unplayable map designated E2M1 can be found in the data files. The map is an unfinished version of Limbo, but many of the required textures are missing in the Alpha. This issue, and the extremely unfinished nature of the design, makes the level completely unplayable and it must thus be seen only as a piece of historical curio.
- Level 1: Not used in the final game. Made by Tom Hall; it is unknown whether it is merely a starting slate or a finished introductory level showcasing the features that were making their way into Doom.
- Level 2: E2M2: Containment Area - Almost identical to the retail version, except for the added exit, crushers in the southernmost corridor and minor changes in the northern crate maze. The exit is blocked by an impassable linedef, and the player can therefore never finish the map. At this point, the map is still "Supply Depot 2".
- Level 3: E2M3: Refinery - Notably the coloured door frame introduced by Tom Hall does not correspond with the needed key, the frame being yellow and key being blue. Disregarding texturing, the level is nearly identical to retail.
- Level 4: E1M7: Computer Station.
- Level 5: E3M3: Pandemonium - The hub nature of the level is less pronounced in this version than is was in the previous Alpha, with the signs leading the player to either the "Laboratory" (LAB) or "Warehouse One" (WH1) replaced by generic gray textures. With the notable exception of texturing, the level is nearly identical to retail.
- Level 6: MAP10: Refueling Base - This level was carried over to Doom 2.
- Level 7: E1M4: Command Control - Of note is this version of the level does not have an exit. The showers and locker rooms from the previous alpha have been removed.
- Level 8: E1M2: Nuclear Plant - This version is virtually identical with the version shipped with Doom 0.4, albeit using different textures, and, where the exit should be, there is a hall leading to the "computer maze", and lacking a chainsaw.
- Level 9: E1M6: Central Processing - Changes from the previous Alpha are slight; a maze in the east of the map has been cut and a corridor at the southern edge has been added. The map was completely overhauled before retail, shrunk by half and lost most of the features present in the Alphas. The level has no apparent exit, but it is possible to reach the next level using "+" and "-" keys while the menu is open.
- Level 10: E1M3: Toxin Refinery - The earliest version of the level made by John Romero.
- Level 11: E2M7: Spawning Vats - Disregarding texturing, the majority of the map--architecture, layout, item and entity placement--is nearly identical to retail.
- Level 12: E1M8: Phobos Anomaly - As the scenario was still Tei Tenga at this point in development, the level was known as simply Anomaly. The caverns (described as mines tunnels) are still there and the hell canyon is still there, as opposed to the star-shaped room in the finished version.
- Level 13: E2M4: Deimos Lab - Disregarding texturing and some later changes the level is almost the same as the retail version; some areas are architecturally 100% identical. The retexturing for retail consisted of applying Hell textures to originally Tech Base areas.
- E2M1: E3M7: Limbo - The level is included in the WAD file, but is unreachable. Even if one manages to get on to the map somehow, the level's textures are missing and causes it to crash. Most of the beginning rooms are present, but almost all the rest of the map is missing.
Powerups that never made it to the released version are present in the data files, and are even placed in some of the levels. For instance, the Vampiric Powerup is placed in the hidden room in the southern crusher corridor of the Containment Area level, instead of the Chainsaw as is the case with Ultimate and registered Doom. Unfortunately, since the code is not present the powerup neither works nor shows up. The corridor did not even have crushers yet.
Some bonus items seem to be carry-overs from Wolfenstein 3D, such as the chalice and the chest. While the purpose of the bonus items were simply to award the player points -- similar to Wolfenstein 3D -- the point system was dropped early in the development of the game, and the bonus items are merely remnants of it. The combat armor/megaarmor is still called officer armor and uses a different sprite (a green armor with boots).
Most of the item graphics were completely different, and utilized a design similar to Wolfenstein 3D, most notable in the mentioned treasures and the pistol clip.
- Demo lumps appear for the first time. There are four of them, DEMO1 to DEMO4.
- The PLAYPAL has the same colors as the previous alpha, with seventeen color indices still undefined and set to pure white, but it has been enhanced to feature eleven levels. Starting from 1, palettes 2 to 8 are progressively redder, and palettes 9 to 11 are progressively brighter. COLORMAP is still set at 32 levels.
- COLORS12, COLORS15, HUFONT and DOOMERR are still around and unchanged.
- The map format is similar to the previous alpha.
- The TEXTURES format has become definitive.
- The Demon, Formerhuman, Imp, Cacodemon, and Baron of Hell have a beta death animation in the .wad.
- Also the above enemies have an beta attack frames.