BBC News By Vikki Blake image copyrightIRON GATE STUDIO image captionAt one stage Valheim could boast 500,000 concurrent players, despite being released in an incomplete "early access" form You wouldn't watch a film without an ending - so why do people buy unfinished video games? An incomplete version of Indie title Valheim - a Norse survival game - released to rip-roaring success earlier this year. Early access releases like Valheim are becoming increasingly common, particularly on PC shops like Steam. By selling the unfinished games, developers can test them as well as bring in extra funding and building up an early fan base.