The general fantasy of the hero is that you juggle between Recon and Sentry modes (very similar to Hammer) but you have unique benefits in both forms. Another big difference is the fact that Bastion's Sentry damage is mostly ability based and to top it off, it's a skillshot that can be blocked by a tank if the situation calls for it. Imagine a Li-ming with a watered down version of Disintegrate from lvl 1 :)
- 2 different forms, static and mobile
- Builds focused on physical or ability damage
- Long range poke is ability based and blockable, as opposed as Sgt Hammer
- Singular ult with multiple upgrades at 20
- Reload mechanic akin to Tracer although watered down.
1 - Quest tier
Here you define more or less if you wanna focus on a certain playstyle or you want to stay flexible for the rest of your build.
4 - Self Peeling tier
At lvl 4 you get some tools to help yourself in situations where the enemy team may try to burst you down.
7 - Utility tier
Vision, a counter to healing and some anti-cc for an immobile character. A little bit of everything.
13 - CC tier
Bastion's cc comes quite a bit late and isn't too much to balance for his potential damage and zoning.
20 - Storm tier
3 ult upgrades to compensate no choice at 10 and a jack of all trades talent if you need the burst of power asap.
Feel free to leave a comment with suggestions or any questions :P
Autoattacks are still lock-on and hitscan (like Hammer's), but his Q ability is a straight line skillshot (Like Muradin's Q).
You can still autoattack with no Sentry Gun ammo, but most of your damage comes from there.
I hope that cleared out things for you :)