Galmedes is a scrolling shooter viewed from the side. The player pilots a spacecraft through sequential stages, destroys enemy units, avoids projectiles and terrain hazards, and survives until each stage boss is defeated.

Progression is based on clearing stages and improving the ship's offensive capability through power-ups or other in-game bonuses. The arcade format emphasizes repeated attempts, score improvement, pattern recognition, and preserving lives for later sections.

Stay mobile while firing continuously, but avoid moving predictably when enemy projectiles begin to overlap. Learn the timing and approach patterns of bosses instead of treating every encounter as a damage race.

Collect offensive upgrades when the route is safe, and prioritize survival over risky score opportunities. Because arcade shooters become more demanding in later stages, conserving lives and recognizing recurring enemy formations are more valuable than aggressive movement.