Diluvian Ultra is a single-player, first-person shooter focusing on a retro aesthetic and fast-paced, strategic combat. The game is set in its own expansive fictive universe. Rather than gritty or dark, Diluvian Ultra is colorful and fantastical, like the cover of pulp sci-fi novels of the past.
The game's core combat revolves around a unique "dual-damage" system. Enemies possess both armor and health. Players must strategically switch between different weapon types - some excel at shredding armor, while others focus on lethal damage. This creates an engaging risk/reward dynamic, as players must carefully balance applying armor-depleting attacks versus saving up for devastating finishing blows.
Mobility and movement also play a key role. The player character can double-jump, dash, and even deflect projectiles with their sword. Chaining these maneuvers together results in a graceful, ballet-like flow to the combat. Skilled players can dart around the battlefield, stripping armor and delivering devastating strikes.
The levels themselves encourage thorough exploration. They feature a Metroidvania-inspired design, with hidden upgrade pickups and power-ups scattered throughout the organic, flesh-and-stone environments. Acquiring these enhancements allows players to customize their arsenal, unlocking alternate fire modes and damage type changes.
Diluvian Ultra's gameplay presents a considerable challenge, especially on the "Diluvian Ultra" difficulty setting. Enemies attack in coordinated groups, forcing players to masterfully manage their weapons, ammo, and positioning. However, those who persevere are rewarded with a profound sense of accomplishment.