[cuong]

I don't know if Valve does this on purpose, but their remake of titles (Team Fortress, Counterstrike, Dota) all keep essentially the same gameplay mechanics but introduce new enhancements (graphics, UI, matchmaking, etc.).

This is important for eSports. Having to learn a new game every 3-4 years so you can follow along is difficult for viewers. It also allows professional players who invest the training to transfer their skills more easily.

It's different with other companies -- Blizzard, for example, created a new game in StarCraft II. It shares a few similarities with Brood War, but the differences are vast. I really, really like Valve's approach.

[NamTaf]

They explicitly stated that Dota 2 would be mechanically identical to Dota 1, to the point where some of of the quirks imposed on Dota 1 due to engine limitations were intentionally reproduced in Dota 2.

It's just started to deviate away from that now, but it is kept remarkably similar - bugs and all. For example, using the item that teleports you a set distance forward teleports you only 80% of its max distance if you click beyond its max.

The other one is 'orb effects' - certain enchantments which add some effect on your standard attack. They do not stack with one another - only one works at a time - except for one of them [1] which does stack with only the life-steal ones.

This makes dota have a learning cliff more than a learning curve, but the depth of the gameplay is pretty crazy as a result.

[1]: http://dota2.gamepedia.com/Eye_of_Skadi

[vidyesh]

Apart from graphics, attack animation, environmental changes and various effects. Dota2 is no different from Dota 1 per se.

All the changes that you see right now in dota2 are now map updates for dota1 ( yes the crazy 6.80 update which essentially changes a lot of gameplay was a (map) update in dota 1 too )

For example, The orb effect had always been that way. 'Orb effect does not stack' Do you remember that on items in dota1? It used to explicitly say that in the item description in dota1. In dota2 they explain it a bit better.

[NamTaf]

Sorry, I wasn't clear: I know that orb effects are identical in dota 1. I am saying that many of the quirks of dota 1 have been carried over to dota 2 - Skadi's orb interactions is one example of that.

One difference, for example, is the interaction between naga siren's net and manta style - in dota 1 it dispells the net, but not dota 2. There are subtle differences like that but they are the exception.