According to programmer Zoid Kirsch, when the team first started working on Phendrana Drifts in Metroid Prime, they created a particle system that shows snow gently falling. When the snow effect was first implemented, they noticed large empty streaks in the falling snow, and quickly realized that the snow was basically a 3D plot of the deficiency of the default random number generator that came with their compiler.

They switched to a using a better random algorithm via a linear congruential generator that was still fast, but generates a far better distribution of numbers, allowing the snow to look much more evenly distributed. This moment was what helped the developers realize just how bad their default random number generator was and that they had to make use of a better one.

When this story was originally posted to Twitter in 2022, several other developers replied with similar shorter anecdotes about working with RNG, such as Robin Lavallée, a programmer on Surf's Up for the Nintendo DS, and Tom Leonard, the lead programmer on Thief: The Dark Project.

In the last few months of the game's development, the team invited friends of family to do "white paper" playtests of the game where they would play without help and the developers would monitor their progress. According to programmer Zoid Kirsch, they learned a lot from these observations:


These tests with new players helped improve the game greatly, because they provided clear feedback in how to communicate the game world to the player, resulting in a lot of simple design changes that were incorporated throughout the game.

If Samus speeds through a Morph Ball puzzle or boosts through a Morph Ball tunnel, sometimes there's a little door blocking the way. According to programmer Zoid Kirsch, these doors were designed to resemble and serve the same purpose as the regular big doors that open once the force field over them is shot and the room behind them is fully loaded.

When they first started making the 2D-styled Morph Ball areas, they were connected to various rooms with tunnels. They worked well until testers started beating the load times of the next room and would fall out of the world. Kirsch had to go throughout the game and add the Morph Ball doors into every tunnel that crossed rooms to ensure that Samus won't roll out of the tunnel and fall into the void before the room is loaded. Because the testers were already conditioned to wait at the big doors after the force field was shot, no players ended up backtracking and waited for the small doors to open, rendering them a successful change. Ideally, players shouldn't see the small doors very often as the load system tries to get the next room loaded, but they might bump into them if they are quick enough.

When you are locked onto a target in Metroid Prime, pressing the jump button does a sideways dash. This lets the player easily strafe around a target and dodge incoming fire. This sideways strafe jump sets a horizontal velocity on the player that continues to circle around the target while locked on, but if you unlock the target just as the strafe jump starts, Samus keeps the horizontal momentum without the lock-on pull. This trick, which the game's speedrunning community called the Scan Dash, allows for a larger horizontal distance traversal than a normal jump. Using this momentum can let Samus catch the edge of the cliff beside her ship in the Landing Site and get the Space Jump Boots early upon landing.

According to programmer Zoid Kirsch, creative use of the game physics and movement that results in acquiring items out of order allows for creative exploration of the game world. While sequence breaks like this are a crucial part of the Metroid series, this trick would actually be patched out in later releases of the game.

According to one of the game's tech leads Jack Mathews, the way the developers were able to keep the game at 60 FPS with four different visors was to make one visor the "baseline," and make sure the others perform as well or better, with tech or design:

• The baseline for all the other visors is the Combat Visor, which provides an unmolested view of the world. It has Samus' Arm Cannon, lightmaps, and allows for plenty of combat. In Mathews' opinion, it's the most beautiful visor, because it's the one the player sees the most.

• The Scan Visor has the baseline elements of the Combat Visor, plus more UI, markers, a zoom window, etc., but it doesn't have the Arm Cannon, projectiles, and their lights. All that performance goes to the visor, which is why everything seen through the scanning window has a low quality blur. According to Mathews, the design of the visor needed a slightly zoomed scan window, but they didn't have the performance to re-render everything or render at a higher resolution, so they just did a digital zoom which blurs things.

• The Thermal Visor does have combat and particles, so the visor's performance comes from the lack of static lightmaps. All world lighting is turned off, and the post-process filters are just a palette lookup. The palette used for the visor was created offline. "Hot" objects used the Z component of the screen-space normal. "Cold" objects used the red component of their albedo texture.

• The X-Ray Visor (created by programmer Ted Chauviere) also has combat and lets the player see through enemies and Samus' Arm Cannon. Everything else, while purported by the game to be see-through in the visor, is essentially the same, and "invisible" objects are just models turned on and off. They also rendered with a white-to-black "fog" so they don't need to render far-away objects, and it's rendered at a lower resolution and blurred. The details of how this fog works involves obscuring the main view and showing depth buffer and normals/normalmaps only (with some trickery for invisible objects), but according to Mathews converting the GameCube depth buffer to something linear on the GPU was extremely expensive, on top of there being no normal maps on the GameCube.

• The Morph Ball Camera also essentially works as a visor, but instead of gun and particles, world shadows are projected on the ball surface (this effect was created by fellow lead technical engineer Andy O'Neal), a projected shadow under the ball, and a constant dynamic light.