Andreessen Horowitz has invested $20 million in a British company that builds 'virtual worlds'

Silicon Valley cash is continuing to flood into Britain.

Andreessen Horowitz has just invested $20 million into Improbable, a London-based startup that is building software to help create "virtual worlds," TechCrunch reports.

Founded in 2012, Improbable doesn't aim to build these worlds itself. Instead, the startup is working to build the underlying infrastructure that other companies can then utilise to create complex environments that thousands of people can interact with. These could be massive gaming multiplayer games - or it could equally be used for urban planning, or modelling the spread of disease.

Virtual worlds are often centralised in a few servers, but Improbable tries to decentralise this. "You can imagine our approach as a swarm of decentralised, heterogeneous workers collaborating together to form a simulation much larger than any single worker can understand," the company explains in a blog post.

Improbable aims to "hide this operational complexity from developers, whilst making it financially viable and easy to build simulated worlds."

Respected venture capital firm Andreessen Horowitz is now investing $20 million into Improbable, with the Financial Times reporting a valuation of around $100 million, citing someone "familiar with the matter." Investor Chris Dixon will be joining Improbable's board as a result.

In a blog post, Dixon says the company has "built an outstanding team of engineers and computer scientists form companies like Google and top UK computer science programs. They've done all of this on a small seed financing, supplemented by customer revenue and research grants. We are thrilled to partner with Improbable on their mission to develop and popularise simulated worlds."

Improbable is just the latest in an increasingly long line of British tech companies benefiting from injections of Silicon Valley capital. Over the last three months, there have been three "unicorns" created - private companies with $1 billion-plus valuations. Music discovery service Shazam raised $30 million at the milestone valuation in January. Boutique online retailer Farfetch also achieved unicorn status in March, with the funding round led by DST, a firm that has previously invested in Twitter, Facebook, Xiaomi and more.

And money transfer service TransferWise is the third, raising $58 million in early 2015, sharing investment firm Andreessen Horowitz with Improbable. The FinTech sector has often benefited from American investment. There's also WorldRemit's $100 million (investor TCV has also backed Facebook, Spotify and Netflix) and Funding Circle, who raised $65 million in 2014 from Accel Partners and Union Square Ventures.

In an interview with Wired in 2014, founder Herman Narula said that Improbable wants to be the "Google of simulation." With this latest funding round, the right people are finally listening.

Disclosure: Marc Andreessen, co-founder of Andreessen Horowitz, is an investor in Business Insider.