What just happened? Doom co-creator John Romero has partnered with metal guitar legend Buckethead and metal album artist Christopher Lovell on the creation of two limited edition box sets for hardcore series fans. For everyone else, Sigil brings 18 levels of original Doom action to the table free of charge.

Monday marks the 25th anniversary of Doom, arguably one of the most influential first-person shooters of all time. To celebrate the occasion, co-creator John Romero has announced an expansion that’ll be arriving in mid-February 2019.

Sigil is the spiritual successor to the fourth episode of Doom, picking up where the original left off. It’ll consist of nine single-player and nine deathmatch levels. Described by Romero as a “megawad,” the expansion will be available free of charge to owners of the original 1993 registered version of Doom.

Hardcore fans may also be interested in the two limited edition physical releases in the pipeline.

The standard edition of Sigil includes a “big box” featuring the artwork of Christopher Lovell, a 16GB USB stick modeled after a 3.5-inch floppy drive, a two-disc jewel case with game data and soundtrack from Buckethead plus two stickers.

The beast box edition, meanwhile, includes an oversized box that is individually numbered and signed by Romero, the same 16GB USB drive, a two-disc booklet style case, an 8 x 10” art print signed by Christopher Lovell, a Sigil-themed coin, a pewter statue of Romero’s head on a spike, a t-shirt and two stickers.

The Sigil fan boxes are available to pre-order through December 24 priced at $39.99 and $166.00, respectively, via Limited Run Games.