After 15 long years, Black Mesa's ambitious reimagining of "Half-Life" finally came to a close with the 1.0 release this past March. That's because Crowbar Collective had yet to announce that they were working on a 1.5 "Definitive Edition" of this fan-favorite remake, not even a finished version.

Then, after seven months of relative silence, Definitive Edition appeared with a detailed blog post explaining the changes; Black Mesa is a 15-year project, with some levels and features literally a decade apart.

The bulk of this new beta is devoted to visually matching some of the game's early maps with the gorgeous Xen levels, the last levels added to Black Mesa before release. Most of the outdoor desert spaces were given brand new models, textures, and subtle color correction.

Back indoors, a new sequence was added to bring the lights back into the power-up chapters, with flickering dynamic lights scattered throughout the location. On A Rail, already heavily modified from the original Valve layout, the silo has been significantly reworked to ensure that the rocket "gets the respect it deserves."

The beta version also makes a number of gameplay changes, rearranging enemy placement and smoothing out collision detection. Controversially, the Definitive Edition also adds Half-Life 2-style supply boxes, which hold health, batteries, or both.

Finally, Steam Workshop support has been improved, expanding the types of mods that can be created and making it easier to filter the Workshop collection; full patch notes for Black Mesa 1.5 can be found in the Steam Announcements post.

Black Mesa: Definitive Edition Beta can be accessed by selecting "public-beta" from the Steam drop-down; with Steam's Halloween sale, Black Mesa is currently 50% off.