Via [url=https://steamcommunity.com/games/CSGO/announcements/detail/498334899948749339]the Steam Community[/url]:

[quote=Valve]A new pre-release build (“1.41.1.3-rc1”) is now available in the CS2 beta depot. This build is not compatible with public matchmaking.

For instructions on how to opt into a CS2 beta depot build, visit the following page:

https://support.steampowered.com/kb_article.php?ref=9847-WHXC-7326[/quote]
[quote=Valve][b][u]ENGINE[/u][/b]
- Updated engine code to the latest version of Source 2.
- Reworked bullet penetration simulation to reduce CPU usage.
- Improved core utilization of some client particle and sound effects processing, reducing overall CPU usage when players are shooting.

[b][u]GAMEPLAY[/u][/b]
- Defusing C4 will now lower the viewmodel weapon, prevent scoping, and delay firing the weapon by 150ms after exiting the defuse.
- Fixed a case where 1 tick was incorrectly subtracted from sv_predictable_damage_tag_ticks.

[b][u]UI[/u][/b]
- Major Highlight clips are now viewable from the Spectator Loadout.
- Selected player is now more visible in the Team Counter.
- Context menu in the Inventory now opens in a position relative to the cursor.
- HUD weapon mode indicator has been moved to the ammo count.

[b][u]MAP SCRIPTING[/u][/b]
- cs_script enums can now be imported and behave the same as TypeScript enums.
- CSWeaponType.PISTOL == 1
- CSWeaponType[1] == "PISTOL"
- Added enums CSRoundEndReason, CSHitGroup, CSLoadoutSlot, CSDamageTypes, CSDamageFlags and CSWeaponAttackType
- Added BOOSTS value to CSGearSlot. This is the gear slot for healthshots.
- Updated Instance.OnRoundEnd to now receive the reason
- Updated Instance.OnBeforePlayerDamage to now receive damageType and damageFlags and the result can now modify damageType and damageFlags
- Updated Instance.OnPlayerDamage to now receive damageType and damageFlags
- Updated Instance.OnKnifeAttack to now receive attackType
- Updated Instance.TraceLine, Instance.TraceSphere and Instance.TraceBox
- The trace config now accepts an array of ignore entities or just one
- The trace config can specify to trace against hitboxes
- The trace result will include hitGroup if tracing against hitboxes
- Updated Instance.BulletTrace result to include hitGroup
- Updated Entity.TakeDamage to accept damageType and damageFlags
- Added CSWeaponData.GetGearSlot()[/quote]

Rumor has it:

- Size is close to 1 GB (with Workshop Tools installed)