Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download SuperTurrets AI Targeting System Free.
SuperTurrets AI Targeting System v2.0
SuperTurrets is a complete targeting system ready for all kind of situations as RTS games, tower defense games or mouse controlled tanks and it is compatible with 3D and 2D games.
This package comes with an AI for aiming and selecting targets and it is quite configurable allowing you change lot of parameters as visibility precision levels, enemy tags or configure the selecting priorities allowing you to get more complex behaviours than traditional turret targeting components.
Top it off, the support for deploy in/out animation, shoot recoil and multi-cannons can increase the visual experience of your project. I will stop talking so you can take a look at videos and features to get a better idea ?
Features Overview v1.0 ● Two-parts rig working in any orientations with configurable speed and angles. ● Three optional areas: Targeting, attacking, too-near. ● Support from 0 to N cannons. ● Fold/Unfold animations before start attacking. ● Dynamic (non animation) recoil foreach cannon. ● Custom inspector and helpers that make your turrets configuration much more easy and fun. ● Enemy/friend system based on tags. ● Visibility tests so turrets will not shot through friends, walls, etc. ● Support for custom priority selection algorithms. Which one you are going to shot first, the strongest or the fastest?. ● Smart AI, turret will switch between enemies in an optimal way. There are public parameters adapt this behavior to your needs. ● Made with performance in mind, you can choose from different visibility tests and add layer masks. You can configure a very simple turret ready for mobile. ● Complete, clean, free of warnings and heavily commented source code included. ● Complete demo project included with an example of enemies, shoots, bullets, particles,scenes, etc. ● An awesome turret 3D model made by a programmer (Me). ● Works on iOS and Unity free version. v2.0 ● 2D Mode! Now you can use all the features in your 2D game with sprites. ● Added vertical angle to clamp turret movement. ● 3D handlers added to configure vertical and horizontal angle limits. ● Fold/Unfold animations now works with Mecanim. No more legacy animations. ● Updated custom inspector. Now you can edit multiple turrets at the same time and everything is better organized. ● Now a SimpleTurret is included if you want something to aim another thing without worrying about AI stuff. ● Improved debug info/gizmos. ● Improved coded architecture (ITurret interface added). ● Custom strategy policies now are scriptable objects. ● Added layer masks for visibility tests.