Build tool: press G to take out the hammer. Pick what to place with Ctrl + mouse wheel (barricade, turret, and the Medic's healing ward or the Heavy's ammo box), click to place, press G again to get your weapon back. Repairing (hold E) now needs the hammer in hand, for bots too.
Holster: press the number of the weapon you hold again to put it away. Ctrl + mouse wheel switches weapon.
See-through scenery: when a player, zombie, turret, healing ward or ammo box is hidden behind a tree, a rock or the Core, that object turns see-through and the hidden one shows through as a coloured outline: red for zombies, blue for players and bots, orange for turrets and ammo boxes, green for the healing ward.
The items panel shows your vest and helmet next to your potion. The potion icon takes the colour of its effect, and drinking one gives a coloured sparkle: green health, red damage, yellow haste, blue speed. Vest and helmet are light blue, in the shop too.
Game event sounds (shield, downed, revived, respawn, joining and leaving players) and footsteps that change with the ground.
Late joiners get a window to pick their profession.
Every class now numbers its own weapons 1, 2, 3 ... up to its last weapon, instead of fixed numbers.
The keys 8, 9 and the old G (barricade, turret, ward, ammo box) are gone: everything you build is on the G tool. Level-up perks are picked by clicking the card (no more 5, 6, 7).
The Heavy now starts with its one barricade. The Medic's healing ward has a new model (a first aid kit).
The Core's health and shield bars only show once the Core is damaged.
The controls panel is now a clean table of keys.
Smarter bots: they fall back to a safe spot when hurt or outnumbered, build barricades where the lane is weakest, take big supply crates as a squad, sprint home after a trip, and the Heavy bot puts its ammo box near the Core.
The grass and bushes no longer disappear and pop back when a portal opens or closes.