I know I'm late to the party, but I would like to add my thoughts, because I think the entire argument is rather silly.
Let me state the obvious first:
Nadeo created a game called TrackMania. TrackMania as a whole is made up of eight environments. The concepts of TrackMania are the same across all environments:
1. Each environment has a car with physics unique from the others.
2. Each environment has a set of blocks with which to create tracks which have underlying characteristics that make them somewhat unique to the others, but conceptually still the same (flat, banked, wallride, loop, turbos, etc.) with a few exceptions (ex: engine killer blocks in Nations Forever)
3. The game engine rules of how a player finishes are the same across all environments, meaning the racer may take any path he/she deems fit ... as long as they make it through each checkpoint and through the finish, it's counted as a complete lap. (this allows the awesome flexibility for authors to create multipath maps.)
Let me state another point before I get to my thoughts:
Many tend to very loosely abuse the words "most" and "all" (myself included) -- even though it may/may not be accurate. It's easier than trying to go research statistics, blah blah blah, but we need to be careful when having a discussion like this. I will try to be careful about how I use it below...
My thoughts (and I hope I can articulate and organize them well; my apologies if not.)
I believe the TrackMania community (even somewhat proven in this thread) is as diverse as the number of players that have participated in any part of it. As a whole it feels like one of the best of all games out there because of the servers I've played on over my time, most of the players I have interacted with have shared a camaraderie and respect for each other. There have been a few exceptions. Now, in that context, realize that I have probably only played on an extremely small subset of the servers that have existed; so I'm in no-wise an authority on what "most" or "all" players think or feel. I believe all of us are in the same boat there.
That said, I will never understand anyone making an argument that only ONE environment from TrackMania should be in eSports. TrackMania is eSports, not any one particular environment. For as many as say Nations/Stadium should be it, there are probably as many that say it should be Island or Canyon or Bay or Rally, etc. My own humble opinion is that the best TrackMania players are those that not only can shine in ALL environments, but in ALL styles of tracks too, not just tech. I know I will be flamed for making such comments, but again, I don't believe there is a true "most" or "all" to be had here. I do believe that a large group have come together as one to create an eSports scene for Stadium because Nadeo released that originally standalone environment for the ESWC... so it was more than appropriate.
However, I have run two professional tournaments of my own, being a complete newb to the eSports scene, but having loved playing TrackMania for years and having our own private tournaments with our team, it was nice to have a venue (GEEX) to try to spread the word about TrackMania to the rest of the world; especially the USA where FrostBeule correctly pointed out that it has never been as big here. I believe the reason for that has been the lack of marketing. A lot of people I know that have discovered TrackMania in the USA found out about it online through other means, or happened to see it while in a game store looking for something else.
Back to my tournaments... I ran two successful tournaments which had corporate sponsors backing them, the most recent being sponsored by Ubisoft themselves who also brought Intel along for the ride. We were able to provide awesome prizes, including gaming laptops, a top-end video card, large widescreen monitor and some awesome CPUs. From what I understand, I ran my tournaments completely different than many in the discussed eSports scene... my first tournament was TMUF and included maps from every environment, and as many different styles as I could find, including a top-down R/C-style map, and one that was built for multi-path called "Kingdom of Tricks." The second tournament was the first official USA TrackMania 2 Canyon tournament.
Another thing I'd like to point out is that my rules would probably make the paid pros upset... I allow spectating and shortcuts. As mentioned before, the game was designed to count a complete lap if the player gets through all the checkpoints and the finish gate. I like that model... I think it has expanded the kinds of tracks that are available since it allows for multipath tracks anyway.
Because shortcuts are allowed, spectating must follow... which is fine, because if someone is unaware of a cut, they can find out about it by watching; they still have to be able to execute it, and have wasted some of their time spectating, leaving them less to actually pull it off.
This works out fine because we don't go find tracks that have secretive cuts in them... we try to get well-tested quality tracks, but if someone in their training has found a better way to accomplish the goal, more power to them -- and in my experience in the community, including in real tournaments like the Verizon PlayLinc tournament the night before TMU's release, people were showing each other cuts they found in those tracks.
Nevertheless, I digress ... but I brought it up because I want to emphasize the point that there are very different ideas about how TrackMania can be an eSport.
Both events were successful, I am under the impression that everyone had a good time and many paid great compliments to me on how much they enjoyed it (including those that didn't win anything.)
The last tournament I had was my greatest feat yet, and completely impossible to pull off on my own. I had the incredible backing of an employee at Ubisoft and nine popular track authors from around the world. And despite some technical difficulties like not having the in-game ads like TMF to announce our event, we were still able to get players registered and playing from across the USA, and even one from Canada. And despite not being able to fund finalists to get to our event, we still had two fly in from opposite ends of the country, one of them taking home the grand prize.
So to say that these kinds of things aren't valid for eSports is incorrect. Yes, these events are going through growing pains; again, we're new at it. But I believe, and I believe there are a lot of others that feel the same (they just haven't been organized into an eSports group or anything), that all of TrackMania is legit for eSports... without the need of whining or fighting with each other. If one group wants to make a Coast-only competition, so be it. If one wants to do Stadium-only with only tech tracks, so be it. If one wants to do Stadium with crazy wallride-based tracks only, more power to them. It just doesn't matter. The game is versatile enough that it can be used in any configuration for any eSports competition. As long as the players know what the specifics are for that particular competition, they're good; and can make their decision on if it's for them or not.
But the point is, TrackMania is eSports, not any one environment and not any one particular style of tracks. I still believe the true best TrackMania players are those that can shine no matter the environment, no matter the style of track.
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Now, all that out, I understand that those that make the game more a career will have a segmented eSports scene that may focus on one environment and one style of track. As mentioned before, that's perfectly fine and valid... but it's not right to say that this can be the only way TrackMania can be in eSports.
FrostBeule, I hope you get to continue enjoying the way you enjoy TMN in the eSports scene. I hope everyone else gets to enjoy it in whatever other aspect TM gets used... I think we should all encourage all uses of TrackMania in eSports.
Ok, I'm finished now... flame away.

(Though I wouldn't mind seeing some of the folks that have participated in my tournaments coming back here and posting their thoughts on the eSports TM tournaments of a different flavor they participated in.)
GG
EDIT: If you got through this entire epic novel; you're freaking awesome... but you should be playing the game, not spending all your time reading about it.
