Over the course of just five weeks, Facepunch Studios' open-world survival title Rust generated 40 percent of the nine-year sales total of Garry's Mod — the sandbox release that studio founder Garry Newman is most famous for.

Rust is currently in Alpha, leaving Newman and the rest of the team surprised by its ability to already dwarf GMod sales.

"We never, ever expected anything to dwarf GMod's success," Newman told Games Industry International. "I did some rough maths this morning: in terms of profits, from sales and royalties, in a month Rust has made about 40 per cent of what GMod has made in about nine years. We can't really believe it."

The game tasks players with gathering resources and crafting all items, including food and wood, to survive. Like DayZ, which it takes inspiration from, players face a number of non-combat related deaths. These include starvation, drowning, hypothermia, attacks from wildlife and exposure to radiation.

"The first thing people do is run around and try and bash people's heads in with a rock! They want to try and get items and build a camp," said Newman. "Then, after a while they simmer down and realize that they kind of need to work with other people, that if they help someone out they'll help them back. It goes back and forth like that."

Rust is currently playable on Windows PC, Mac and Linux via Steam.