CS2 replaced the old static smoke billboard with a volumetric object that reacts to the world around it. Valve's own feature page calls smoke "dynamic volumetric objects that interact with the environment, and react to lighting, gunfire, and explosions". That is a bigger change than it sounds, because it means a smoke is no longer a wall that stays exactly where you threw it.
What the smoke reacts to
Bullets and HE grenades push smoke. Valve's page states that "bullets and HE grenades can push smoke to briefly clear sightlines or expand occlusion", so a few rounds into a cloud, or a well placed HE, can open a gap you did not make yourself.
Smoke also expands to fill the space it is in. It seeps out of opened doorways and broken windows, travels up and down stairs, expands along long corridors, and combines with other smokes. A smoke is not a wall that stops where you threw it. It fills whatever space is available, and the page lists doorways, windows, stairs and corridors as the places that matters.
On top of that, smoke particles work with the lighting system, so a cloud reads differently depending on the area it sits in.
What this means when you hold an angle
- Do not treat a smoke as solid for its whole duration. Check it, and expect the edges to thin out once shots land in it.
- An HE grenade is now a tool for reopening a sightline, not only a damage tool.
- Two smokes fill a corridor more reliably than one, and a smoke at a doorway drifts through it once the door opens.
- The same behaviour helps the other team. A smoke that has been pushed is a smoke you can walk through.
Valve's feature page describes the system as it launched. The current change log at counter-strike.net/news/updates is where smoke changes would show up, and the recent entries do not list one. If you are reading this after a later update, that page is the place to check whether anything has shifted.
Frequently asked questions
- Does a smoke still block vision? Yes, it still occludes, but its shape is no longer fixed.
- Can I shoot through my own smoke? Bullets push it, so you can open a small gap for a moment.
- Does smoke move through doors? Yes, it seeps out of opened doorways and broken windows, and it goes up and down stairs.
- Do smokes combine? Yes, Valve's page says they combine with other smokes.
- Does lighting change how it looks? Yes, smoke particles work with the unified lighting system.
Valve, Counter-Strike 2 features page (responsive smokes)
Valve, Counter-Strike 2: Responsive Smokes (video)
Valve, Counter-Strike 2 update notes