On 2 servers with real players, out of 4 Steam servers that run it now, fakes and empty ones included. Checked 10:36 UTC.
inner_city is a community map, not one of the maps that come with the game. Servers send it to players from the Workshop when they join.
Over the last 30 days inner_city was the #538 map on CS2 community servers, with 3 real players on it at any moment on average - 0% of everyone playing. It ran on about <1 servers with real players at a time. Right now 13 people play it on 2 servers, most of them on servers in Kazakhstan and Russia. It is busiest on Saturday around 15:00 UTC and quietest on Monday around 05:00 UTC.
Right now 13, on 2 servers from the Steam server list. Over the last 30 days it had 3 real players on average at any moment. Fake servers and bots are not counted, and Valve matchmaking is not in the list.
On Saturday around 15:00 UTC. The grid above shows every hour of the week in your own time zone.
The busiest right now: CS2 MANIAC #52 [KZ] — CYBERSHOKE.NET (CLASSIC) (8 players), CS2 MANIAC #19 [RU] — CYBERSHOKE.NET (CLASSIC) (5 players), CS2 MANIAC #34 [UA] — CYBERSHOKE.NET (CLASSIC) (0 players). The full list is under "Servers running it now", and every server has its own page with its history.
de_mirage43,206 players on average
de_dust217,866 players on average
sandstone_fb14,462 players on average
de_mirage_fps6,334 players on average
awp_lego_25,427 players on average
awp_lego_2_fb4,847 players on average
de_mirage_christmas2,848 players on average
<null>1,274 players on average
bhop_emevaelx31,053 players on average
duels_mirage_1x1998 players on average
de_inferno892 players on average
de_nuke764 players on average
KZ
RU