how can i make game like this one with unity (2d,2.5d)

game like this.

With hard work and talented team.

There are no real shortcuts. Make great sacrifices of your social life, learn Unity inside out, learn art inside out, learn everything you can about the platform, play test with people and have serious alpha and beta stages.

You should bring this further to the Unity forums then search questions about:

How do I give touch input for mobile devices?

How do I make an inventory?

How do I make 2d in Unity3d?

Can I make a MMORPG with Unity?