In patch 0.13.2, was added the Christmas Event, in which: a christmas room was added to the hub, gifts that are scattered across the levels, Christmas -themed treats and decorations.
To open a room in the hub, you need to collect 10 gifts, that is, one from each level (including -1).
This is how the door to the event room looks:

You should put the gifts under the Christmas tree. The only option for collecting gifts is to complete the game to the hub, so that you can enter each level. At the same time, you can have two gifts with you (each is 2×3 in size). You can open gifts to get a Christmas treat (stat-wise, like regular consumables) or a regular consumable
Attention
Gifts can be found not only in the places described, but also in some other places on the level
Level 0
Can be found on the floor


Level -1
Can be found on the floor/table


Level 1
Can be found on table in rooms



Level 2
Can be found on tables in rooms/corridors


Level 3
Can be found on tables



Level 4
Can be found on floor/tables


Level 6
Can be found on tables(?)


Level 37
Can be found on the elevation of the pool (jump and press F for take)


Level !
Can be found on medical furniture in corridors between safe rooms (grab it carefully while running)
Level FUN
Can be found on floor in parkour (place before maze with yellow entity)


Christmas room
Put the gifts under the Christmas tree (press F with gift(s) in the inventory). After you put all 10 gifts, the room will open:

Inside, it will be dark, and there will be a staircase that you need to descend and open a door to enter this room:

There will be many gifts under the Christmas tree:

This is how the gifts look in the inventory:

Each of them contains a Santa Claus hat

That’s all I could find

Inside, it will be dark, and there will be a staircase that you need to descend and open a door to enter this room:

There will be many gifts under the Christmas tree:

This is how the gifts look in the inventory:

Each of them contains a Santa Claus hat

That’s all I could find