In Iosis, you control the Silver Guard, which protects the base from waves of corrupted metals with collisions. The main source of damage is momentum; the faster you are, the harder you hit. You can die and respawn in combat as long as your base is intact. As you progress through fast-paced runs, you will build your play style according to several aspects such as mobility, self-sacrifice, manipulation and control.

Iosis is inspired from bullet hell and tower defense genres with a special emphasis on customizable runs that allow unique builds. Dying as the Silver Guard is only a temporary setback which unlocks builds that depend on self-damage and unleashes devastating power.

• Collision-based close combat: The core combat depends on the momentum of the player as the main damage source. Basically, the faster you move, the higher the damage you deal. Becoming a massive object is also a way to increase your damage output but be careful not to restrict your mobility too much.

  

• Over 60 collectible upgrades: In Iosis, the collectible upgrades come in various categories such as active spells, passive residues, unique power-ups and Vitriol seals. Residues are of various types; parametric upgrades, periodically activated effects, triggered effects based on collisions and dash-triggered to name a bunch. Spells work like weapons that generally define the core aspect of your build. Unique power-ups are powerful additions offering drastic additions to the power curve while seals offer upgrades to the Vitriol Vessel itself.
  

• Challenging enemy waves: The corruption of Aleno conquered all the lesser metals, Copper, Mercury, Iron, Lead and Tin. Increasingly powerful waves of corrupted metals seek to harm and destroy the Vessel. You need to develop defensive mechanisms to negate their combat advantages.
  
  

• 3 linearly progressive stages: Progress through the layers of alchemical space: Gates, Fountains and Towers. You will find the influence of Aleno increasing as you get closer and closer to the final confrontation.

Iosis is inspired from occult alchemy themes where the main goal is to stop the corruption of Aleno and achieve purification through the four stages of alchemy: Nigredo, Albedo, Citrinitas, Rubedo. Protect the base which bears the Philosopher's Stone and undo the corruption that holds captive all metals.