Doom's newest update — aptly numbered 6.66 — retires the game's premium season pass and makes all of its multiplayer DLC content available to all players. It also revises Doom's multiplayer progression system and makes a slew of other changes.

The multiplayer DLC that is now free is are the Unto the Evil, Hell Followed and Bloodfall packs, which rolled out between August and December of last year. They delivered nine maps, three more guns and three playable demons, plus armor customizations and special abilities.

The season pass for all the DLC originally cost $39.99.

Additionally, update 6.66 overhauls Doom's unlocking system for additional guns, equipment, playable demons and customizations. It will move from a random unlock to one where items unlock according to meeting specific level requirements or completing in-game challenges.

"Now, if there’s a specific helmet you want, you can work toward unlocking it by focusing your play style on the related challenge," Marty Stratton, Doom's director, said in a blog post.

Veteran players will have the option of keeping all of the items they have unlocked (or paid for) prior to this progression change, or doing a full reset to experience the new progression system. In any case, everyone's level gets reset to 0. All veteran players will get a special badge noting their prior experience with the game, and those who reached the max Slayer level will get another one for that.

Elsewhere, the Hack Module System is being replaced by a Runes System similar to the one from the single-player campaign. Runes are persistent abilities included in a loadout that, unlike Hack Modules, don't expire and don't need to be activated.

Several other changes, tweaks, fixes and alterations (including to the in-game HUD) are described in the Bethesda Blog post.

For those who don't have the game, Bethesda has cut Doom's price to $14.99 (on digital marketplaces only). Windows PC and Xbox One players can also try it over a free weekend beginning Thursday, July 20, at noon for Xbox One and 1 p.m. for PC. PlayStation 4 owners can try a a free weekend beginning noon on Thursday July 27. The free trial offers the first two levels of the single-player campaign and unlimited play in its online multiplayer. Any progression earned in the free trial carries over to a full purchase.