DUOtris is an excellent puzzler from Binary Zoo, makers of Mono and DUO. The name may be slightly misleading as the player is not required to make lines but instead link three or more blocks of the same color together to remove them from the screen.

Throw in the challenge of having two separate grids, requiring the player to shift and arrange two pieces at the same time and you have the makings of a fantastic game. You're allowed to swap pieces by pressing CTRL or space, although this option can only be used if none of the pieces has touched another block. The game ends if any of the accumulated stacks goes over the line at the top and bottom of the screen. Some blocks carry power-ups which, when destroyed, may help or hinder your progress.

Name: DUOtris
Developer: Binary Zoo
Category: Puzzle
Type: Freeware
Size: 5MB