One Button Boss is a pixel-art bullet hell game where you face off against a single, relentless boss that grows deadlier with every defeat. Dodge waves of projectiles, graze bullets for bonus points, and dash through the boss to deal damage — all wrapped in a retro arcade aesthetic with CRT scanlines and synthesized audio.
| Input | Action |
|---|---|
| WASD | Move in four directions |
| Mouse | Hold to move toward cursor position |
| Space | Dash (grants brief invincibility) |
Dash cooldown is displayed as a ring around your character — it pulses when ready.
- Dash Attack: Dash through the boss to deal damage. This is your only way to hurt it.
- Graze: Skim past bullets without getting hit to earn bonus points. The closer you fly, the higher the reward.
- I-Frames: After taking damage, you get 2 seconds of invincibility (your character flashes during this time).
- Slow Motion: Near-miss moments trigger a brief slow-motion effect, giving you a split second to react.
The boss shifts through three phases as its health drops. Each phase change grants the boss a 3-second shield (it flashes white during this time and cannot take damage).
- Phase 1 (Health > 70%) — Predictable fan shots and circular bursts. Learn the patterns here.
- Phase 2 (Health 30–70%) — Rotating barrages, explosive bullets, and homing projectiles join the fight.
- Phase 3 (Health < 30%) — Full bullet hell. Cross barrages from screen edges, fake-out bullets, warning zone attacks, spiral storms, and slow zones that appear at your position and reduce your movement speed by 50%.
- Wave 1: Bullets deal 1 HP per hit.
- Wave 2+: Bullets deal 1.5 HP per hit.
HP is displayed as 3 hearts in the HUD, with support for half-heart display.
Each time you defeat the boss, pick one of four upgrades before the next round begins:
| Upgrade | Effect |
|---|---|
| DASH SPD | Reduce dash cooldown by 20% (multiplicative) |
| DASH DST | Increase dash distance by 30% (multiplicative) |
| SPEED UP | Increase movement speed by 20% (multiplicative) |
| LIFE STEAL | Heal half a heart when you dash through the boss (once per dash) |
After selecting an upgrade, you receive 3 seconds of invincibility.
| Action | Points |
|---|---|
| Dash Attack (hit boss) | +100 per frame of overlap |
| Graze (per bullet) | +10 |
| Boss Defeat | +5,000 |
After each boss defeat, the boss respawns stronger — more health, faster attacks, quicker movement. Stack your upgrades wisely and see how many waves you can survive. Normal mode ends after 3 waves.
- Dashing makes you invincible. Use it to dodge through dense bullet patterns, not just to attack.
- Graze aggressively in Phase 1 while the patterns are forgiving — build your score early.
- Save your dash for emergencies in Phase 3. The cooldown matters.
- Life Steal heals half a heart per dash — play aggressively to sustain.
- Speed Up stacks multiplicatively — it can make dodging much easier in later waves.
- In Phase 3, watch out for pink slow zones that spawn at your position. Keep moving to escape them.