Arkans

Each player has 20 square tiles and each tile is numbered on all 4 sides. On your turn, you place a tile from your hand onto the board with a 5 by 5 grid. The placed tile must be adjacent to at least another tile already placed with all adjacent numbers matching (with the effect that you refill your hand) or (partly) with adjacent lower numbers (with the effect that all tiles with lower numbers are removed from the game).