On 0 servers with real players, out of 1 Steam servers that run it now, fakes and empty ones included. Checked 01:36 UTC.
de_boulder is a community bomb defusal map: the Terrorists plant the bomb, the Counter-Terrorists stop them or defuse it. 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 de_boulder was the #748 map on CS2 community servers, with 2 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 0 people play it on 0 servers. It is busiest on Friday around 23:00 UTC and quietest on Monday around 09:00 UTC.
Right now 0, on 0 servers from the Steam server list. Over the last 30 days it had 2 real players on average at any moment. Fake servers and bots are not counted, and Valve matchmaking is not in the list.
On Friday around 23:00 UTC. The grid above shows every hour of the week in your own time zone.
The busiest right now: R1ngelp1et2 CS2 Server (0 players). The full list is under "Servers running it now", and every server has its own page with its history.
de_mirage43,229 players on average
de_dust217,882 players on average
sandstone_fb14,410 players on average
de_mirage_fps6,319 players on average
awp_lego_25,428 players on average
awp_lego_2_fb4,821 players on average
de_mirage_christmas2,848 players on average
<null>1,276 players on average
bhop_emevaelx31,051 players on average
duels_mirage_1x11,026 players on average
de_inferno889 players on average
de_nuke759 players on average