love the idea. the precedent is there from cs_office - in the old days if my memory isn't failing me it used to be openable only from the CT side of the garage but was later changed.
there is nothing wrong with the idea but be prepared to move the button based on playtests:
- perhaps putting the button next to the B site entrance would work, perhaps putting the button right next to the door in Mid works best - perhaps players don't make the connection between the button and the door, etc. As long as you can approach it with an open mind.
and be prepared to make the timer shorter:
- 10 seconds is a long time in-game, maybe the door simply opening slowly so after 1 second you can throw flashes and smokes through the gap, and after 3 seconds you can begin crouching to get underneath it, but your movement is slowed because of this, and by 5 seconds you can just run straight in.
and be prepared to not go down the route of global countdowns:
- global sounds in CSGO are a bit overpowering, if you are trying to listen to someone on the other side of the map and there is a lot of ambient noise it will interfere with the gameplay, if the sound of the door opening just happens to be quite loud and audible from 2048 units then sure, it gives audio cues to players nearby - and if the button is pressed randomly by a player then they would need to communicate that they have done so instead of letting the map tell them, further increasing the need for communication between teams.
personally i think it's neat to have these kind of things, they are just extensions of doors or breakable windows or metal panels that can be broken. this is just another tool to add variety and a unique flavour to a map, and like i said it's been done before in official maps and players learn to deal with the gameplay it offers.
don't be put off by 'pro players' who only want a static map with zero props and fullbright lighting,