There's a somewhat worrying trend appearing in PC gaming in the last few years. Just yesterday I was browsing the featured games on Steam's front page (on that scrollable area), and out of 14 featured games, six were either pre-purchase offers or early-access offers. In other words, almost half of them. A pre-purchase offer means simply buying the game before it has been published. In other words, pay now, get the game when it comes out. Oftentimes (although in some cases not) there will be a very minor incentive to pre-purchase the game, such as a slightly reduced cost (eg. 45€ instead of 50€) or some extra content (which usually just means a few extra props that are rather inconsequential from a gameplay perspective.) In the worst cases you don't get any advantage at all for pre-purchasing. Before the prevalence of Steam (and other such applications), ie. when basically all games were purchased as physical discs, there might have been a slight "advantage"...