Site: https://www.moddb.com/mods/zircon-engine
More pics: https://www.moddb.com/mods/quake3-quake1-mapping-resources/images
Quake3_Quake1 is a mod making dozens of DarkPlaces extensions easily accessible for mapping.
cmdline: darkplaces.exe -game quake3_quake1 or zircon.exe -game quake3_quake1 (Unzip to quake/quake3_quake1 folder)
2 flagship single player maps: Geoplanetary Station and The Hotel showcase a fair share of the several hundred features made available (DP + QC + CSQC + Q3 bsp version 46 capabilities).
Released yesterday, hit Top 50 at Moddb getting tons of views.
https://media.moddb.com/images/mods/1/59/58205/map_a1000_geo.jpg
https://media.moddb.com/images/downloads/1/252/251795/quake3_quake1_v1.jpg
There are keypads, books, npc dialogs, emitters, attachments, cabinents, func_text, rotating doors, mechanical contraptions, vehicles and other stuff on display.
https://media.moddb.com/images/members/5/4671/4670468/profileshots/map_a1000_hotel.jpg
As this uses an advanced form of the Quake 3 map format, there is no limit to texture resolution. The monsters, items, weapons are high resolution.
https://media.moddb.com/images/members/5/4671/4670468/profile/electrical_hazard.jpg
https://media.moddb.com/images/mods/1/59/58205/q3q1_smoke.jpg
Quake3_Quake1 is open source.
(This is a submitted for consideration as a news post.)