I built anti-cheat systems for CS2
Hey everyone. I’m the developer of CS2FOW and CS2AC, two server-side protection systems built for Counter-Strike 2 community servers.
CS2FOW
CS2FOW is a server-side anti-wallhack system.
Normally, a player’s game client always receives information about enemies even behind walls. A wallhack reads that information and displays those enemies. CS2FOW checks whether an enemy should actually be visible before allowing the server to transmit them using LOS (Line-Of-Sight).
The system combines PVS, BVH8, and AVX processing. In simple terms, PVS quickly skips players who cannot possibly be visible, while BVH8 performs detailed map-geometry checks only when necessary.
https://reddit.com/link/1vq30z7/video/q4skmiberrjh1/player
Depending on player positions, PVS can reduce the visibility work by up to 86% and sometimes skip 100% of those calculations.
Because hidden enemies are no longer rendered by the client, my testing also showed an average client FPS improvement of around 20%. Results naturally vary depending on the map, player count, hardware, and how many enemies would otherwise be rendered.
https://reddit.com/link/1vq30z7/video/xditgocxprjh1/player
https://reddit.com/link/1vq30z7/video/f5lyqwuyprjh1/player
What information does CS2FOW remove?
CS2FOW filters hidden enemy entities (player, weapon & related child entities). It doesn't remove sounds like footsteps/gunshots or erase information about an enemy the player already saw.
Doors, breakable objects, and moving props are not currently treated as visibility blockers. If a map or its prepared geometry cannot be used safely, CS2FOW leaves players visible instead of risking incorrect hiding.
Does it support Workshop maps?
Yes. CS2FOW includes an automatic map baker that prepares what it needs in the background, usually within a few seconds.
There is also a separate baking website only used as a backup for hosting environments where the built-in baker cannot run.
Does high ping have issues?
No. The system dynamically adjusts the amount of preload that player gets depending on their ping. Here's an example of 120ms ping on de_mirage.
https://reddit.com/link/1vq30z7/video/wl4n7e9dtrjh1/player
CS2AC
CS2AC is a server-side behavioral anti-cheat. It analyzes the aim, shots, movement, button presses, subtick commands, and game settings that players already send to the server.
It contains 19 independent detection modules.
Combat
- Aimbot detects blatant snaps, snap-returns, smooth aim assistance, and more humanized aim curves around damaging shots.
- Aimlock detects machine-like tracking that stays attached to a moving enemy, including through walls.
- Triggerbot detects repeated shots fired with unrealistically fast timing when the crosshair first reaches an enemy.
- Silent Aim detects damaging shots that do not match the player’s visible aim movement, while accounting for normal weapon spread and inaccuracy.
- Inhuman Accuracy detects consistently abnormal accuracy when the player is already aiming close enough to a real enemy.
- Precision Anomaly detects unusually clean long-range rifle headshot patterns across different enemies and rounds.
- Irregular Behavior detects repeated rage-level results involving airborne shots, no-scopes, long-range headshots, and wallbangs.
https://reddit.com/link/1vq30z7/video/d3h80m7gurjh1/player
Movement
- Autostrafe detects automated air movement through repeated turning, speed, and timing patterns.
- Bhop detects automated bunny hopping through landing timing and repeated jump-input patterns.
- Hyperscroll detects excessive jump commands combined with an abnormally high number of perfect landings.
- Nulls detects scripts that switch between opposite movement keys with machine-perfect timing.
Client and input manipulation
- Anti-Aim detects impossible view angles, spinning, repeating jitter patterns, and unnatural attack-return movements.
- DLL Injection detects suspicious event subscriptions exposed to the server by certain injected clients. It does not scan the player’s computer or files.
- Desubticking detects movement commands whose normal subtick timing has repeatedly been removed.
- Doubletap detects the same weapon firing twice within an impossible amount of server time.
- Invalid CVar detects protected or impossible client setting values reported to the server.
- Invalid Input detects malformed movement commands where held, pressed, and released buttons contradict one another.
- Namechanger detects rapid name-changing used to create spam or confusion.
- Subtick Spam detects excessive movement or aim changes placed at the same moment inside a server update.
CS2AC does not judge someone from one lucky shot or one generic suspicion score. Every module has its own evidence requirements and safety checks.
The aiming modules combine repeated behavior and consider normal weapon behavior, network conditions, distance, movement, accuracy, wallbangs, smoke, airborne shots, and no-scopes where relevant.
When enough evidence is collected, CS2AC produces a readable report explaining what happened. Reports can be sent to the server console, Discord, or another platform. Server owners remain in control of how each detection is handled.
Public messages and evidence reports support 37 languages.
Do players need to install anything?
No. Both projects run entirely on the CS2 dedicated server as Metamod plugins. Players do not need to download or install anything.
Windows and Linux servers are supported.
What happened to the public repositories?
After my GitHub account was restricted by mass reports and the projects were repeatedly repackaged and sold without following their licenses, I moved future development to private repositories.
CS2FOW and CS2AC are both still actively developed but privately.
I’m grateful to everyone who tested the projects. They became much larger than I originally expected, and I’m genuinely proud of how far they have come.
If you have questions or simply want to reach me, you can do it here or on Discord. My username is the same on both: karola3vax.
Thanks.
