Thanks to the launch of a new expansion pack, Studio Wildcard's Ark Survival Evolved has taken over the Steam Top Ten.

The Aberration DLC was released on December 12th. As well as charting in fifth place, this appears to have driven sales of the game's Season Pass - which came in third place, as well as sales of the base game, which charts No.8.

Grand Theft Auto V holds second place, while the Year Three season pass for Rainbow Six: Siege comes in at the No.4 spot. Given that Ubisoft has its own digital storefront in Uplay, sales of this content pass are likely much higher.

As of the end of that game's second series, it has more than 25m players having somehow added five million since May.

Early Access post-apocalyptic title They Are Billions from Numantian Games is this week's No.6 spot. That game launched on December 12th and already has a wealth of positive reviews. SteamSpy pegs sales at being in the region of 74,000 copies.

The VR version of Fallout 4 charts at seventh, with Capcom's Okami HD remaster debuting in ninth place. SteamSpy puts owners as in the region of 57,000 people.

Last week's No.5, Getting Over It with Bennett Foddy, drops five places to No.10.

Here is the Steam Top Ten for the week ending December 17th:

1. Playerunknown's Battlegrounds, PUBG Corp
2. Grand Theft Auto V, Rockstar
3. Ark: Survival Evolved Season Pass, Studio Wildcard
4. Tom Clancy's Rainbow Six Siege: Year Three Pass, Ubisoft
5. Ark: Aberration - Expansion Pack, Studio Wildcard
6. They Are Billions, Numantian Games
7. Fallout 4 VR, Bethesda
8. Ark: Survival Evolved, Studio Wildcard
9. Okami HD, Capcom
10. Getting Over It with Bennett Foddy, Bennett Foddy