Click an empty position to place your man.
A move consists of walking straight in one of the four orthogonal directions until you encounter a block.
The blocks are of different colour. After each of your step, a differently coloured set of blocks shrinks, the sequence being yellow, red, purple, blue, yellow,.... The next colour to be shrunk is shown at the top center border.

A shrunken block can be walked on and walked over as if it would not be there, and when you do so, it will disappear. A counter at the top counts these unblocking moves.

You win when you eliminate all blocks.
If you don't manage to eliminate all blocks, try make as many unblocking moves as possible (or leave as few blocks on the board as possible).
Solutions are attached.

When SmartMoves is activated, you simply click the target position to move your man. Activate it via View/Options/Board/SmartMoves.