Caltron 6 in 1

Caltron 6 in 1 is a multicart published in for the Nintendo Entertainment System in North America, and the only game known to be released by Caltron, a Taiwan-based video game company. In Australia, it was published under the title Real Players Pack by Home Entertainment Suppliers (HES). This version is regarded by collectors as the rarest HES game; on the 22nd January an auction of eBay had 2 bids up to US $2850. Dynacom released the cartridge as Multi Acao 6-in-1 for the Brazilian market.

6–in–1, as its title suggests, consists of six different games of various genres. The games included, which are mostly clones of other popular video games of the era, are Cosmos Cop, Adam and Eve, Magic Carpet 1001, Balloon Monster, Porter, and Bookyman. These games were all previously released separately in Famicom format by NTDEC.

The compilation has received poor reviews, with one reviewer claiming that all six games on the multicart are "uniformly awful [and] barely first-generation NES quality," even though they are more playable and are of "much higher quality" than other unlicensed video game compilations, specifically citing Active Enterprises' Action 52 as the comparative example.

Games
The six games on Caltron 6–in–1 are:
 * Cosmos Cop is a pseudo-3D into-the-screen shoot 'em up that is similar to Sega's Space Harrier. However, the game experiences a lot of image–breakup on the screen due to the NES's limited capability of handling first–person scaling.
 * Magic Carpet 1001 is a horizontal scrolling shooter that was later released on pirate cartridges as Aladdin III and with some graphical and sound modifications as Super Harry Potter. The game has been criticized for its steep difficulty curve. It is the only game on the cartridge that is not an obvious clone of another popular title.
 * Balloon Monster is a clone of Mitchell's Pang and the North American equivalent Buster Bros.
 * Adam and Eve is a single-screen platform game similar to Nintendo's Balloon Fight (itself based on Williams' Joust) in which the player has to kill snakes by bursting the balloons attached to their heads. This game also received criticism in that the game — despite its title — had very little relevance to the biblical story of Adam and Eve.
 * Porter is a puzzle game similar to Thinking Rabbit's Sokoban and Boxxle where the player has to move boxes into specifically–marked places. This game is criticized for its awkward controls; boxes can only be moved while holding down the A button, and if the B button is accidentally pressed, the level automatically restarts without any warning to the player.
 * Bookyman is a direct clone of Williams' Make Trax and Kural's arcade game Crush Roller. This game has been considered an inferior clone of their arcade counterparts.

Myriad version
When Caltron Industries, Inc. was going out of business, Myriad Games, Inc., a company based in Kingwood, Texas, bought all of their existing inventory of cartridges. Myriad then took the carts and added a very generic (no graphic art) label. They were then packaged in custom boxes with a folded manual. Each Myriad cart and box were numbered individually.

Myriad's only change to Caltron's product was to replace the label with their own. In fact, you can see the edges of the Caltron label visible at the edges, as the Myriad label is slightly too small to cover it. No programming changes were done, hence the game is exactly the same. To this point, the title screen still reads "Caltron." The six games on the cart are identical to Caltron's release.

Shortly after the release of 6-in-1, Myriad went out of business for unknown reasons. The game has become one of the rarest unlicensed games made for the NES. Collectors speculate that fewer than 100 copies of this game still exist, and even fewer are complete. The most valuable copies of the game are those with box, instructions, and the cartridge with matching serial numbers. The lowest known serial number is 000032 and the highest is 000888. At least two sealed versions are known to exist.