6 - Outlaw sports - Multiplatform
What do you do when you've got a decent idea for a sports series but there's no way in hell people are going to buy it over EA or Nintendo's offerings? Add girl after slutty, stereotypical girl. The first game in the series, Outlaw Golf, was a surprisingly fun and featured title that also happened to have gallons of potty humor and lap dances on the putting green. After a few tours through the course, however, the high-school-level jokes begin to wear thin and suddenly girls hitting other girls with golf clubs isn't as hot as it once was.
As the series crept into volleyball and tennis courts it continued the ultra-generic humor but decided not to elevate the gaming experience in any way. The first time, fine, we'll let you slip away with a so-so game and a few low brow chuckles. By the second or third try (fourth if you count Volleyball Remixed) there needs to be something else. Native American chicks sucker-punching smartass UK punks isn't going to sell anyone - but half-naked Native American chicks doing anything at all will at least make us do a double take. If the franchise had relied less on its cookie-cutter "offensive" material it might still be around today.
Above: If they weren't here, you wouldn't be either
5 - Ar tonelico - PS2
Right? If you played it, you know. At first it seems like a normal anime RPG. Cute girls, a fun-n-furious battle system, some catchy tunes, all the typical bases are covered. But after a few hours, gal pals Aurica and Misha invite you to explore their nether regions by way of Matrix-style jacking in. Turns out they've got feelings and emotional baggage and all that and you're the only guy in the whole world that understands their pain. What a lucky, lucky man you are.
As Reyva Teils, the two girls have ports on their body that you have to, um, "enter." And if you thought that explanation was awkward, try reading some of the thinly veiled dialogue. Aurica's never done this before, so she's afraid it'll hurt when you put it in ("it" being a stat-enhancing Grathnode Crystal) and needs you to be gentle on her first time. Misha, on the other hand, is all prepped and ready to go. Dive in all you want. Look around. Make yourself comfortable.
The underlying idea at work in tonelico is called moe (mo-eh), where fans will intensely identify with a female character due to her saccharine cuteness or naïve outlook on life. It's usually not a sexual attraction, but c'mon, look at those girls. They've got sex written all over their faces and the developers know it. Anime and RPG fans are generally gonna dig any cute heroine they see in a game, but allowing them to metaphorically bang two girls back to back, over and over again is the sweetest icing on the biggest cake ever imagined. Doesn't hurt that it's a solid RPG too - just not one that's overly different from the Atelier Iris games. Good thing there's some lovin' to keep things interesting.