Oases is a logic puzzle. A rectangular or square grid contains circles with numbers in some cells. The goal is to blacken some cells (leaving the other cells white) so that the unshaded cells must be connected horizontally or vertically. Blackened cells should not share an edge. Cells with circles cannot be blackened. Unshaded cells must not cover an area of size 2 x 2. Each circled number represents the number of other circles that can be reached from that circle by only going through empty (unshaded and uncircled) cells. (A circle that can be reached by more than one path still only counts as one circle for counting purposes.)
Cross+A can solve puzzles from 3 x 3 to 30 x 30.