Inside gags, for better or worse, are a staple of videogames, whether they're in the form of hidden characters, outright parody of the competition or just another tired reference to Monty Python and the Holy Grail snuck in by a translator. If you're not in the know, most of them will shoot right over your head. If you are, they can range from dull to chuckle-worthy, but either way you'll feel a tiny surge of pride for picking up on them.

And then there are the geeky little references that are just kind of cool independent of whatever it is they're referencing. The ones that, whether you're geeky enough to get them or not, add something special to the game they're in. And in the case of this article, the ones you should get anyway, because they're referencing other games. What follows is a look at the very best of these, along with a bit of explanation for those of you who - for whatever strange, non-geeky reason - still don't get it.

7. The DOOMed Marine
Duke Nukem 3D | 1996 | PC, PSone, N64

Half action-packed gorefest, half comedic romp, 1996's Duke Nukem 3D was jammed full of weird little asides and in-jokes, but none stuck out as much as the relatively good-natured jab it took at its competition. Early into the game's prison-themed third level, you'll come across a creepy-looking chapel, and if Duke flips a semi-hidden switch, its true nature will be revealed: the lights glow red, and the giant cross behind the altar flips upside-down. But if you squeeze into the secret area that this transformation opens up, you'll find a then-familiar badass - the space marine from DOOM - torn in half and splattered all over the floor in the back. Just in case you don't get the joke, Duke makes sure to hit you over the head with it by growling, "That's one DOOMed space marine!" Thank you, Duke. The five people who played your game without ever having played DOOM first are in your debt.