Duke Nukem 3D, a FPS game featuring the titular pastiche of action heroes of the 80s and 90s, with all the corny lines and questionable macho-attitude, received a Japanese release for the PC, and in that vein it came with a manual.

The translation work for this manual is the standard fare of polite language and explaining English terms via either direct translations or simply spelling them out in katakana.

One of the trademarks of the game is its XTREME sense of 90s phrases and one does not get too far into the game, in fact the very difficulty selection screen, wherein as per the tradition of games from the same decade the usual labelling of easy - medium - hard and so on, were rendered in phrases fitting into the themes of the game itself.

Hence, Heretic and Hexen featured faux-Shakespearean English ("Thou needeth a wet-nurse" for he easiest degree), DOOM 1 and 2 had its varying degrees of implying just how relentless the player was a glutton for punishing difficulty, such as the middlemost one being named "Hurt me plenty."

Thus we arrive at the Ducal difficulty settings:

I will see if I can cover stuff like this in the future.
Wherein much explicating, majuscule lettering and 90s movie taglines were seen. 

We will take these one at a time:

"PIECE OF CAKE"  (朝飯前だぜ)

The name for the first and easiest difficulty level, the slang phrase here very much implying that it will be an unhindered metaphorical perambulation in the park, and the Japanese translator uses the expression asameshi da ze, "It's a damn piece of cake," but literally "It is before breakfast", a figure of speech implying that something is less than a challenge. Note the emphatic particle ze that has a masculine tone to it and adds something akin to "It's damn easy."

"LET'S ROCK" (軽くぶちかますか)

"Let's rock", the primordial quote to precipitate any manner of stylish arse-kicking in many an action film and game, and we get what would on surface level look like a mistaken usage of keigo (i.e. -masu), but in fact is the phrase buchikamasu with the adverb karuku and the question particle ka at the end, thus "Y'want a slight thrashing, eh?"

"COME GET SOME"(いくらでも来やがれ)

"Come get some" which is not a formal invitation to supper and wine, but merely once more a cocky taunt. Here the Japanese translator gives it as Ikura demo ki yagare (Come fuckin' at me as much as you like!), with ki-yagare using the imperative form of yagaru a verb denoting a disagreeable action on behalf of one's interlocutor.

"DAMN (sic) I'M GOOD"(畜生、俺ってすげぇぜ!)

The braggart giving his own self-evaluation, which the Japanese translation renders as Chikushou, ore tte sugee ze! ("Damn! I s'pose, I'm awesome!"), with chikushou beng an all-purpose expletive, using the assertive male pronoun ore and sugee, a colloquial pronunciation of sugoi ("awesome/cool"), all topped off with ze, the assertive emphatic particle.

Thus, Duke Nukem's egocentricity is carried across in translation.