Hello Csaba,
to bad the was no notice on the internal dev list.
Considering you have left TTDPatch, Marcin too and Josef, I haven't seen a life signal from him since ages, I don't think I will come back too. (But it's a result of other reasons too)
And yes your Graph prove what I thought already since quite a time.
Your reasons why you choose OTTD are quite identical to mine, but there is one well known reason I won't and I can't simple ignore. Why can't someone magical resolve the fact so I can work on OTTD too?
*
About the development style, I think the switching to svn actually was a key point for a rise of development time spent on TTDPatch, because the ideas got more easy into the code. And you got faster and easier feedback.
Without svn I don't think the last stuff would have been made. One key problem is the interdependencies between Patch features that bite back more and more. As more parts on TTD are patched 3 or 5 times the more problems you get. However our way of self contained code worked quite well for the project and the way of TTDPatch works. If the challenge is to make your code work with the other code it won't be any fun. I think the main point on being a Patchdev is and was the challenge to work in the concept of TTD. (And to make it optional)
The most time on last commits was to get all stuff work together without breaking stuff.
I wish you a lot of fun and new ideas with OpenTTD.
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* It's not that I didn't tried it myself.