Shmup Design · June 30, 2026
Pickup and Item Routing in Shmups: Magnet Radius, Auto-Collect, and Economy Design
The pickup system in a shmup is not just a collection mechanic — it is an economy that determines how power, scoring, and defensive resources flow through a run. Most players never consciously model this economy, but they respond to it precisely: they chase items on a good run and abandon items when under pressure, and the design of how items move on screen determines whether those choices feel meaningful or arbitrary. A well-designed item routing system creates micro-decisions that express skill without requiring the player to understand the underlying math.
Published June 30, 2026
Item categories and their movement behaviour
The first design decision is how each item type moves after spawning. Different movement modes serve different purposes:
| Item type | Default movement | Reason |
|---|---|---|
| Power item (small) | Slow drift downward, small lateral spread | Collectable in natural play without requiring detour |
| Point item (large) | Moderate drift downward | Opportunity cost: collecting requires positioning choice |
| Bomb item | Slow float, slight oscillation | Defensive resource; made visible and collectable easily |
| Life extend / 1UP | Stationary or very slow | Extremely high value; player should have ample time to collect |
| Graze charge item | Drifts toward player slowly | Passive resource flow that rewards staying in play |
Items that scroll off the bottom of the screen should vanish without penalty in casual play, but in scoring-focused modes their loss is a meaningful cost that the player should feel. This is set per item type, not globally.
Magnet radius and auto-collect triggers
The magnet radius is the zone around the player within which items accelerate toward the player instead of continuing their default drift path. When the player enters magnet range of an item, the item re-routes its movement to pursue the player until collected or until the player moves out of range.
Magnet radius size creates a tradeoff curve: a large radius makes the game feel generous and reduces item-chase micromanagement; a small radius rewards precise collection positioning. Most shmups use a magnet radius of approximately 1.5 to 2.5 player-sprite-widths — large enough that moving toward an item a short distance catches it naturally, small enough that deliberately reaching for items under fire has a cost.
Auto-collect is a triggered state in which all on-screen items simultaneously route toward the player regardless of distance. Common triggers for auto-collect:
- Power-full: When the player reaches maximum power level, all subsequent power items on screen convert to points and are auto-collected, preventing waste.
- Bomb detonation: Many shmups collect all on-screen items when a bomb fires as a bonus for using the defensive resource.
- Reaching the top of the screen: In some systems (classic Cave shmups), the player reaching the upper portion of the screen triggers full-screen item collection — a risk-reward that encourages aggressive forward positioning.
- Special item pickup: A dedicated auto-collect item (often called a POC trigger, point of collection) activates the state on pickup.
Value-by-position mechanics
One of the most elegant scoring systems in the shmup genre is value-by-collection-position: point items are worth their maximum value if collected at the top of the screen and progressively less if collected lower. The exact value the player receives depends not on which item they collected, but on where on the screen they were when they collected it.
This creates a persistent incentive to maintain high screen position that has nothing to do with safety and everything to do with scoring. Players who understand the system will push into the upper half of the screen during safe windows to maximise point item value, which coincidentally produces the most visually exciting play because it puts the player close to enemy formations.
Implementation is simple: collect position Y coordinate is sampled at collection time, mapped to a value multiplier between 0.5x (bottom) and 1.0x (top), and applied to the base item value. The visual feedback is a different colour or size popup for maximum-value versus standard-value collection.
Item routing on player hit
When the player takes damage, the items they have not yet collected need a routing decision. Three common approaches:
- Items stay in place: The player respawns and must navigate back to collect them. Punishing but fair — skilled players can recover the economy.
- Items convert to a smaller version: Full power items become half-power items after the death, preserving some economy with a deliberate penalty.
- Items disappear: Harsh. Appropriate only for hardcore modes where the economic penalty for death should be severe.
The most important design rule: whatever happens to items on player hit should be consistent and visible. If items disappear instantly and silently on death, players will not understand why their power level reset after respawning. A clear visual transition (items flash and shrink, or flash and vanish) communicates the economy consequence of the death event.
Testing the pickup feel
Pickup systems have a tactile quality that is not visible from code — the satisfaction of items snapping toward the player in a collection sweep is a physical sensation that depends on magnet acceleration speed, collection sound design, and the visual pop of the collection confirmation. Tune the magnet acceleration speed (how fast items route toward the player once attracted) by feel: too slow, and collection feels sticky and uncertain; too fast, and items teleport to the player before the satisfaction of the chase registers.
A collection sweep during auto-collect should feel like a reward: items stream in over a short duration (0.3–0.5 seconds for a full screen clear) with a burst sound and a brief score counter. This is a moment of positive feedback that the player is paying attention to, and it should feel proportionate to the achievement that triggered it.