Early this morning Valve released a new update for CS:GO Beta. This update includes a new gameplay mode called Arms Race. This mode is pretty much the same as the GunGame mod from CS. There is a single extended round with instant respawn(think team deathmatch). All players start with the same weapon, they will recieve a new weapon each time they kill an enemy. After the player has successfully killed their enemies will all guns, they will be left with a knife. The first player to get a kill with all weapons will win the match.
Three new weapons have been introduced in this beta update, they include the following:
The full changelog can be seen below