67%Strong matchEtaine: Magic Survivor / 伊泰恩:魔法幸存者
88%21088% positive reviews, Very Positive across 210 reviews·Female Protagonist · Nudity
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"If it's even, halve it. If it's odd, triple it and add one." This single rule transforms into a brain-melting, high-speed action game. Based on the Collatz Conjecture—math's greatest unsolved mystery—comes a brand-new reflex-testing roguelike!
EVEN OR ODD 1
SteamBeat a mathematical enigma with pure reflexes.

The Collatz Conjecture—an elegantly simple yet infuriatingly complex mystery that has baffled mathematicians for decades—sets the stage for Even or Odd 1. Reduce monsters casting "number magic" down to "1" to purify their souls.
Read the incoming magic numbers in a split second. If it's Even, smash [↑]! If it's Odd, smash [↓]! In this extreme battle where a single hesitation means certain death, chain flawless combos and experience the overwhelming satisfaction of forcing massive numbers to instantly converge into a single "1".
◆ Brain-Melting "Even/Odd" Action
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Enemies will unleash a relentless barrage of numbers. Instantly determine if they are even or odd and strike back with the correct magic. Chain correct answers to multiply your power, reduce the enemy's number to "1", and obliterate them with a devastating Finisher!
◆ Perfect Parries & Just Defense
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Don't just take the hits. Read the trajectory of enemy attacks and strike back at the exact right moment to turn the tide of battle. When backed into a corner, unleash the "Auto-Parry" to survive impossible bullet hells.
◆ Death, Rebirth, and Grimoires
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Death is not the end. Return to "Heaven" and use your collected currency to permanently upgrade your stats. Discover and equip over 10 different Grimoires (magic books) with unique effects to continuously push your abilities to the limit.
◆ The Mystery of the Endless Calculation
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You play as "Ichi", an amnesiac protagonist. Why must she fight? And what truly awaits her at the end of this endless calculation...?
◆ 90 Achievements
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Track your mastery across 9 categories, including Max Combos, Highest Floor Reached, and Max Damage. Can you unlock all 90 achievements and leave your mark on the trajectory of this endless calculation?
Steam data © 2026 Valve Corporation. Trademarks are property of their respective owners.
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The best games like EVEN OR ODD 1 are Etaine: Magic Survivor / 伊泰恩:魔法幸存者, Dice Player One, Castle of no Escape 2, MidBoss, and FORCED SHOWDOWN.
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