Third Is 3D

For a period in the Eighties, it was not uncommon for the third film in a series to be released in 3D. With the current flood of 3D film releases, this has once again become common practice. It may or may not also be set in a foreign country.

Also, a common trend in the times of the first Video Game 3D Leaps, was to have two 2D games, and make the third a 3D one, with titles such as:
 * Ultra Super Death Gore Fest Chainsawer 3000
 * Ultra Super Death Gorefest Chainsawer 2 Chainsaw Good!
 * Ultra Super Death Gorefest Chainsawer 3-D

Film

 * Amityville 3D
 * Jaws 3
 * Friday the 13th Part 3
 * Ice Age
 * Jackass
 * Men in Black 3
 * Piranha 3D
 * The Ring
 * Spy Kids
 * Taken even further with the fourth Spy Kids movie, which was released 4D (scratch and sniff).
 * Step Up
 * Toy Story
 * Toy Story is an interesting case, because unlike the others on this list, it doesn't specifically market 3-D as its defining selling point, despite being released in both viewing formats. It's hugely indicated by the marketer's decision not to call it "Toy Story 3-D". It's all very refreshing.
 * Before the third film was released the first two were re-released in the 3D format as well.
 * Transformers: Dark of the Moon
 * A Very Harold & Kumar 3D Christmas
 * Zombi 3D

Video Games

 * Duke Nukem
 * Earthworm Jim
 * Grand Theft Auto III, while not the first three dimensional game in the series (as the first two also had a height dimension), was the first to feature three-dimensional camera angles, in contrast to its forerunners' top-down views.
 * Variation with the third Kojima-designed Metal Gear game, which was titled Metal Gear Solid instead of Metal Gear 3D.
 * For the series's debut on the Nintendo 3DS, they opted to use the third game in the series, Metal Gear Solid 3 Snake Eater.
 * Prince of Persia
 * Splinter Cell, for the 3DS remake of Chaos Theory, the third game in the series.
 * Wolfenstein 3D. First there were the two Apple games, and then id Software bought the rights to the title and released Wolfenstein 3D (even though the Apple games don't really belong to the Wolfenstein series.)
 * The official title of Doom 3 is actually Doom³, the "cubed" is interpreted by some as meaning "3D". This one is interesting, as it announced a switch from "fake" 3D to "true" polygon-based 3D.
 * The Catacomb series: Catacomb, Catacomb II... Catacomb 3-D.
 * Sly 3 parodied this by giving the game 3D sections to be used with the glasses included in the case. Effectively making it the game that followed the movie method.
 * Marvel vs. Capcom 3 has 3D visuals. The play mechanics and hit-boxes still remain 2D.
 * Simon the Sorcerer
 * Bubsy the Bobcat is another one, but it killed the series.
 * Fallout 1 and 2 were isometric... and you can guess where this is going... Like Duke Nukem, however, there were a few Gaiden Games between 2 and 3.
 * Railroad Tycoon.
 * Dangeresque 3: The Criminal Projective...in 3D!, though that one changed medium from web toon to graphical adventure game.
 * Worms 3D wasn't anywhere close to being the third game in the series, but since Worms 2 was the only one to have a number before it...
 * Puzzle Bobble 3 was titled Bust-a-Move 3DX in some countries.
 * If you consider the light-gun game Ghoul Panic as part of the Point Blank series, then it marks the spot where the games switched from 2D to full 3D characters and environments.
 * Micro Machines V3 and Sonic 3D Flickies Island are aversions, as they weren't actually the third game in the series.
 * Played straight with Sonic 3. While it wasn't a 3D game, the title screen actually used pre-rendered 3D as opposed to the pixel art tile screens in the first 2.
 * There have been so many unnumbered prequels and interquels released since the release of Kingdom Hearts II that the fanbase has gotten completely fed up and seems unwilling to accept a game not specifically called "Kingdom Hearts III" as being Kingdom Hearts III, but it's been officially announced that the upcoming 3DS title, subtitled "Dream Drop Distance", is in fact the third game in the mainline series.
 * The third DJ Hero game would have been a Nintendo 3DS spin-off entitled DJ Hero 3D. The game appears to have been cancelled, however. You have Warriors of Rock to blame for it (although Activision has acknowledged that had DJ Hero not existed to begin with, Guitar Hero may still be up and running).
 * The 3DS itself, if you take the DS as the first and D Si as the second (and dismiss the Lite and XL as revisions)
 * Super Paper Mario is the third game in it's series. It's main gimmick? Flipping into 3D.