Enigma is a GNU game available in Linux distributions. It is available to Debian as an APT module. It is a hybrid of Oxyd, Sokoban, Marble Madness with a dose of Harry Potter thrown in.
Oxyd
The objective of each level (apart from the meditations, see below) is to find and visit all the oxyds on the level. Oxyds are square blocks which light up with a colour when touched, but sometimes, you will find blocks which look like oxyds but aren't. There are always an even number of oxyds - pairs of each colour. You need to visit both members of a pair in succession, when they will stay lit. Touching a different coloured oxyd will reset an unmatched one which is lit.
You have control of a black marble, and three lives in which to complete the level (but sometimes a software setting only gives you a single life). You push the marble using the mouse, and can pick up objects lying in the grid by moving onto the squares where the objects are.
The bottom display shows your inventory of up to 12 objects, including spare lives you haven't used. Right mouse click cycles the inventory. Left mouse click uses or drops the leftmost object in your inventory.
Some levels don't have oxyds, but are meditations. Instead of controlling one black marble, you control 4 white balls, simultaneously. The idea of these levels is to get all four balls into designated pits at the same time.
Whereas Sokoban itself is an abstract puzzle based on a finite sequence of moves, Enigma's version involves using your black marble to move the blocks. These blocks are hit rather than pushed, resulting in a recoil. This recoil could result in you unintentionally pushing back another block behind you.
There are also a variety of different floor surfaces, with different frictional characteristics. These include ice rinks and space (where you get no control of your movement at all, continuing according to Newton's First Law of motion). There are also inverse floors where you move right to go left, up to go down, etc. Some floors have slopes, others lethality if you stay in one place for too long.
Many levels have water, which is lethal (your ball can't swim). But you can build bridges by pushing special wooden blocks onto the water.
Some levels have laser beams, for which the beam itself is lethal, but usually useful serving some other purpose: illuminating an oxyd otherwise unaccessible, or morphing objects in its path. There are also prism and mirror blocks, which can be pushed and rotated to divert the beam.
There are a variety of controls, which can do things such as turning on or off a laser, opening or closing a gate, etc. These include triggers, switches, key locks and coin slots.
Summary
The hundreds of levels that come with the distribution provide a wide range of puzzles, mazes, obstacle courses, tight ropes and other challenges, some of which are extremely difficult bordering on the impossible. For the complete enthusiast, it's possible to create your own levels - the game is open source, and there is an active mailing list for developers.
There's no save function, for persisting your ball mid-level, which is a shame for the more difficult levels. Many an hour has been wasted trying to crack these levels, nearly successfully, only to make a ridiculous mistake at the end.
I've found some bugs in the game. Some levels which refuse to load, freeze up, or segfault. But after all, this is free software.
A fully working mouse is essential to play this game; problems with the tracker ball would make some of the simpler levels trying, and render the more difficult levels unplayable.
In short, this game is highly addictive and extremely playable. Not recommended for those suffering from RSI - this could exacerbate your problems, and you will probably get frustrated losing on the levels that need fine dexterity. Verdict: worth booting up a Linux distro just to play - though I gather a Mac version and Windows binaries are available.