Each level of Braindom sets a small riddle, and the answer is rarely where you would expect it. The brain teasers come with a slice of history too: progress unlocks facts about notable people from history.
When an answer seems too obvious, read the question once more, because the levels hinge on spotting precisely what is wanted. Puzzles that rely on strict logic rather than tricks are found in Sudoku Classic and Minesweeper Online.