Halo shouldn't really be a 'hidden gem', but I'd wager you totally missed out on this one thanks to a combination of series fatigue (we'd had the trilogy, ODST and Reach within just a few years), and the fact that Bungie had left, giving the reigns to 343 Industries. Thing is, the fans hated this too - mainly because the opening cutscene dove into the wider lore and addressed the fact that Master Chief is less a near-mute super-soldier, and more a lab experiment gone awry, the addition of Cortana being a potential suppressant to a wayward personality. That relationship is at the heart of H4, and it's why it's one of the most memorable of the whole lot, purely on a narrative sense. Alongside that you've got the heft of Microsoft's budget backing everything up, which sees 343 introduce some cool new set-pieces to the fold; one of which is a Star Fox-style flight section to close out the game. Halo 5 is the most recent instalment from the team, but it's in taking the franchise down a far more personal route that really makes part four worth a look.
