Quod. \ˈkwäd\. British slang for prison. Very few games teach you new vocabulary words while entertaining you, but BubbleQuod, a physics-based puzzle-platformer from Ukrainian developer Garbuz Games, manages to do both quite ably.
To free yourself from your self-constructed prison to keep out the dangers of the world, you must roll across fifty stages and seek the bubble-bursting pin. The developers offer two levels of difficulty: "normal," which allows for in-air control, and "hard," which is more realistic.
Physics games are inherently tied to the success of their physics engine, and here BubbleQuod mostly passes. The bubble can be finicky at first, but after a few levels the controls become second nature. The objects with which to interact are varied, and introduced with enough frequency to stave off boredom until the difficulty curve takes over. (Said curve may be a bit unbalanced: difficulty increases quickly around level 20, and the last few levels may cause stress-induced baldness.)
The graphics are beautiful, with backgrounds evoking an inventor's workbook, scribbled with notations and designs. The music loop may get repetitive after a few levels, but a mute button is close at hand.
There are ten languages available, ranging from English and Spanish to Russian and Portuguese, but dialogue is kept to a minimum. It's just as well; this is a game that holds its own in any language.