Chaos Break is from the Japanese arcade game Chaos Heat and the gameplay is similar.
Story. The story involves a renegade lab experiment gone wrong and a group of military specialists who have to go in and investigate. You may have heard this game is like Resident Evil, but that is where the similarity ends. You choose to play as either Rick or Mitsuki (who loves short shorts). From there you investigate the facility in a free-roaming 3-D world.
Controls & Action. If you've played Overblood 2, you will be comfortable with Chaos Break. The action takes place in real time. You have your trusty energy-shot gun, the ammo for which you must find throughout the levels. Then you have your special weapon, which essentially clears the screen when you use it. You also have CQC moves, but these are basically useless against the tougher enemies.
Puzzles. Not bad. They aren't hard.
Mood. I was reminded of The Thing for the PS2 when playing Chaos Break. The monsters are a lot alike. However, I prefer the anime feel of Chaos Break. The environments were not meticulously built to creep you out, but some of them are nice to admire. The voice acting will be the thing that breaks the mood of the game. (Actually I guess that's something else it has in common with Resident Evil.)
Ending(s). Multiple endings for both characters. The endings largely depend on one of the main puzzles in the middle of the game where you must save a female lab technician. To be honest, though, the endings were short and forgettable.
More. Chaos Break is a rare action-horror game for the PS1. It was only released in Japan and Europe. A complete copy will likely run upwards of $20 USD. If PSone horror is your thing (like it is mine), give it a try. It belongs alongside Hell Night and Necronomicon as games that should've been imported to America but never were.