Ataru Gun (アタールガン) is a recurring weapon in the games and a gadget in the Manga.
The gun shoots big round homing bullets with eyes which hits the enemy no matter where they go.
In Doraemon Nobita no Machi SOS
In this game this gadget, along with all other gadgets in Doraemon's pocket except a couple, is covered with slime and can't be used unless the player collects 5 Sprays to clean the slime. Then it can be used by any character.
It works just like in the Manga, it locks on the enemies and inflicts moderate damage.
In Doraemon Nobita to Midori no Kyojinhei
In this game, the gadget is unlocked when Nobita and Doraemon enters a water puddle while minimised, and Air Cannon or Umatake doesn't work in water. Doraemon takes out the gadget so Nobita can clear out the enemies. It still can lock on enemies.
Unlike Nobita no Machi SOS, this gadget is locked to Nobita in this game, so Doraemon is unable to use it.
- This gadget is waterproof and can be used in water in Nobita to Midori no Kyojinhei, but it can't be used in water in Nobita no Machi SOS. This reason for change is unknown.