The Expansion Pak allows the random access memory (RAM) of the Nintendo 64 console to increase from 4 megabytes (MB) to 8 MB of contiguous main memory. With the help of an included key, the Expansion Pak fits into the slot that is below a removable panel on the top of the N64 console. Game developers can take advantage of the increased memory in several ways, including making games that are more visually appealing. Some games will allow players to choose a "high-resolution" option, increasing the screen resolution from 320 by 240 pixels to as much as 640 by 480 pixels--creating crisp, high-definition graphics. The Expansion Pak utilizes Nintendo 64's capability for 32-bit, 16.7-million-color display with 256 levels of transparency (alpha)--bringing your games to a new level of realism. Instead of reusing texture data, games can buffer a larger number of textures for a more distinct look.

Other ways for developers to utilize the larger memory is by setting a higher frame rate, longer replays, and more animations. Games also can have more sophisticated artificial intelligence, which allows computer-controlled characters to be smarter, literally. Games can offer more characters and vehicles, and contain larger, more complex levels and worlds. Some games like The Legend of Zelda: Majora's Mask require the Expansion Pak, while others such as Perfect Dark require it for access to all of the game's levels and features