Rock Monsters are initially scarce, but appear with increasing regularity as the game goes on. Energy Crystals add to the player's score, and are obtained by driving vehicles through them. Between missions, the player must use points generated by collecting Crystals and purchase items, such as repair kits for the vehicles in case of damage, or Dynamite, which can be used to clear obstructions from offscreen. A special points bonus of 1000 is given if none of the vehicles sustain damage during the mission. This also eliminates the need to purchase repair kits.