So, recently (a few days ago as of writing) there was a leak of Boreal Alyph. I was lucky to snag it from a post I saw, and thought to share it here for preservation, and/or interest of others.
Link:
https://mega.nz/file/sv0DkZqS#Xkd_L-QZriINxgrOfIVPSqTsJvRuHAzH4G0Tp8-kLaIPassword, if needed: Xkd_L-QZriINxgrOfIVPSqTsJvRuHAzH4G0Tp8-kLaI
NOW. Before you jump the ship and go "WOAH It's real! this is huge!!!"
There's only... Technically a few "functional" maps done. Most maps here are broken, test/dev maps, or zoo's. There's not much to be said about them.
Note: while testing maps, I discovered that pressing tab enables a devmode. Go ham with that!

List of maps in functionality, on my machine (tested on Linux and Windows):
Works:
ba_town
breachpoint
demo_dockyard1
demo_dockyard_pr_footage
devtest_reverboverhaul
dev_ambienttest
dev_asset_zoo
dev_radiation (has nothing functional)
dev_scrapyard_v4 (works, crashed once on start.)
dev_scrapyard_v7
dev_treesway
HonzaMap
mines
pr_art_showcase_garage
pr_art_showcase_intro
spire_tower
the_void (empty map)
white_forest_asset_test
zoo_dockyard
zoo_russian_town
sdk_shader_sample
Runs poorly (low fps):
pr_art_showcase_studio
breachpointv2
Crashes:
pr_dockyard_demo
I hope to see the guns at least ported to vanilla HL2, they feel nice! Except the AR2. Why is it that way.
Update #1:
Huge shoutout to Shift for sharing the newer stable build!
New maps that were added:
ba_background01 (start screen wallpaper)
ba_svalbard_mine_test (empty, short map)
bunkertrain_test
dawn_atmostest
demo_dockyard1_nocrash (polished version of dockyard)
demo_dockyard2 (noclip after 2nd gate)
demo_roxy_powerplant1
demo_roxy_powerplant2 (demo maps, nothing special)
demo_roxy_soldier_flare_deploy (test map, deploying a flare.)
demo_village
parallax_cubemaps_test (self explanatory...)
pyramiden_house_of_culture01 (go to the right end side)
test_fmod_director.
Removed:
pr_dockyard_demo.
Link:
https://archive.org/details/boreal-alyph-b0.5.1498-stableMEGA link: Eventually...TM