Prism

When the light is blocked by a space monster, the Glowbos risk starvation until a race of light-emitting creatures called Bulboids (effectively controlled by the player) arrive to save them.

The basic principle of the game is to bend rays of light (which always travel at right angles) so that they hit colour-coded targets at the edge of the playing area (an 8x8 grid).

To achieve this the player can move any of the pieces (Bulboids, mirrors, coloured filters, prisms, etc.) on the grid.

Pieces can be dragged to any free space on the board (so you don’t have to shuffle pieces about as you would with a sliding tile puzzle) but cannot be rotated.

The game features a “time attack” arcade mode (where the player must clear randomly-generated levels to earn extra time), a free play mode which removes the timer, a puzzle mode where the player must complete increasingly difficult handmade levels, and (in the PC version only) a fast-paced shooting gallery mode where targets and playing pieces are dropped onto the board intermittently, and the player must constantly rearrange the pieces to hit all the targets before they go critical.

Prism for Nintendo DS is currently worth €27.55 loose, €5.38 complete in box, and €10.50 factory sealed. Prices are based on real sales and update regularly on Gamevaro.

Prism has a steady sales history on the tracked marketplaces, meaning it trades hands regularly and isn't considered particularly rare.

Loose means cartridge or disc only, CIB (complete in box) includes the original box and manual, and sealed means factory-sealed and never opened. For Prism, loose is €27.55 and CIB is €5.38 — CIB commands a premium because original boxes and manuals are fragile and often don't survive.

The PAL version of Prism is currently worth €27.55 loose, versus €7.30 for NTSC-U. Regional price differences usually come down to print run size and regional collector demand.