[quote=@MrFoxNews]
40k.  Serious. 
[/quote]

Green chavs with cobbled together scrap machines that literally only function as they do because they believe they do = serious. 

Massive, multi-turreted tanks that make the T-35, Neubaufahrzeug and T-28 look like reasonable propositions = serious.

[s]Imperial Guard[/s] Astra Millitarum being comprised of tons of different regiments of assorted silly hats and time periods = serious. Notable mentions being the guys that look like the good guys from Zulu, the guys that are WW1 Francebritagermany: Clones Edition, the guys that are WW2 Germany, the guys that are Lawrence of Arabia: The Faction, Space Mongols... I wish I had the handy dandy visual charts of major [s]Imperial Guard[/s] Astra Militarum regiments on hand, but I do not.

I could go on forever.
 
To be fair, the setting has long distanced itself from its initial purely satirical origins, but there's still a lot of silliness to be found. Not that I'm complaining, I love how over the top 40k is, but there's loads of better examples out there as far as serious settings go.