Altiax - the same crystals description

Field contains crystals. Crystals are arranged in pairs in table.
Player has one crystal.
Player selects a one column, and player's crystal collides with a pair of crystals located at bottom of column.
If a pair of crystals contains same crystal that has player, player's crystal and the same crystal in pair disappear, player gets remaining crystal and gets score.
Sometimes crystals is scrolled down.
Game end when crystals reach bottom.