On 3 servers with real players, out of 6 Steam servers that run it now, fakes and empty ones included. Checked 22:16 UTC.
surf_nyx is a surf map: you slide along sloped ramps instead of running. It is not one of the maps that come with the game, so servers send it to players from the Workshop when they join.
Over the last 30 days surf_nyx was the #184 map on CS2 community servers, with 23 real players on it at any moment on average - 0% of everyone playing. It ran on about 3 servers with real players at a time. Right now 30 people play it on 3 servers, most of them on servers in Russia and Germany. It is busiest on Thursday around 18:00 UTC and quietest on Wednesday around 22:00 UTC, when about 59.6 times fewer people play it.
Right now 30, on 3 servers from the Steam server list. Over the last 30 days it had 23 real players on average at any moment. Fake servers and bots are not counted, and Valve matchmaking is not in the list.
On Thursday around 18:00 UTC. The grid above shows every hour of the week in your own time zone.
The busiest right now: CS2 SURF #11 [RU] — CYBERSHOKE.NET (TIER 1-2 - EASY, ONLY NYX (19 players), SURFHEAVEN.eu #1 (Easy) (9 players), CS2 SURF #71 [DE] — CYBERSHOKE.NET (TIER 1-2 - EASY, ONLY NYX (2 players). The full list is under "Servers running it now", and every server has its own page with its history.
de_mirage43,435 players on average
de_dust217,954 players on average
sandstone_fb14,462 players on average
de_mirage_fps6,353 players on average
awp_lego_25,446 players on average
awp_lego_2_fb4,846 players on average
de_mirage_christmas2,847 players on average
<null>1,270 players on average
bhop_emevaelx31,056 players on average
duels_mirage_1x11,027 players on average
de_inferno916 players on average
de_nuke788 players on average
RU
DE