Chains is a physics-based action-puzzle game based on linking similarly-coloured bubbles, with twenty levels of varying goals and gameplay elements.
The only common factor on all levels are the presence of coloured bubbles. Most levels follow a fairly similar pattern, however, with bubbles entering the game field at the top and falling onto a structure, where the player then attempts to chain them together to remove them. Chains must be at least three bubbles long, with no upper limit; the bubbles themselves are not constrained to a grid and so chains can go in any direction and even pass through moving bubbles. Bubbles also vary in size, with larger bubbles able to link further than smaller ones.
The game does not pause while making a chain, although bubbles being used do have any movement slowed slightly. Completing a chain 'pops' the bubbles, with the game either spawning an equivalent number of random bubbles to replace them or a constant stream already entering.
Many levels include physics-based elements, including time- or weight-based triggers that will move (or remove) the bubbles, balanced platforms, barriers and rotating elements. Others levels rely more on strategy than reflexes, and require the player to make specific chains.
Due to the colour-based gameplay, the game includes a colourblind mode.
The game has the standard three levels of difficulty - easy, normal and hard. Higher difficulties increase the number of possible colours and rate of bubble creation, but level goals remain the same.
Each level has a specific goal to achieve, which unlocks the next level on first completion. The only way to pass a level is to reach its goal, although play can optionally continue after. There is no direct numeric score for levels, but records are kept for each (which specific records depend on which make sense for that level):
- Longest chain
- Most cleared
- Longest playing time
- Fastest completion
- Optimal completion
- Trident - Clear 100
- The Gate - Clear 200 without losing any
- Exact Change - Match the given amount in one chain
- The Stream - Keep the stream flowing for 5 minutes
- Grid - Link 15 or more together
- Dispenser - Don't lose more than 100 in the next 5 minutes
- Gulliver - Clear 100 by linking 10 chains or less
- Gravity - Link 30 or more together
- Clamps - Clear 300 without losing any
- Pyramid - Clear all
- Coathanger - Clear 300 without losing more than 30
- Jaws - Clear 200 but beware of the spikes
- Pile - Link 40 or more together
- Artillery - Don't lose more than 100 in the next 5 minutes
- The Perfectionist - Clear all coloured bubbles
- The Plant - Don't lose any for the next 6 minutes
- Flippers - Clear 300 without losing more than 5
- Scale - Balance the scale to a zero difference
- The Mill - Clear 300 without losing more than 20
- Time Dilation - Don't lose more than you've cleared for 3 minutes