Sounds way too good to be truth. Some of it sounds believable though, but that's only because whoever wrote this went with a major educational guess. Let me give it a rundown:
amiibo: even more amiibo than the dedicated Splatoon amiibo will be compatible with the game. You can get additional equipment from them. If you touch a Mario amiibo to the Wii U Gamepad, you can unlock a Mario cap.
This seems to be based off how Nintendo's been handling the Amiibos for other games, so it definitely wouldn't be out of the question if they decided to have Splatoon support this feature (Sonic hat plz).
2D Arcade shooter mode revealed: In this mode you can play a 2D shooter game, in which it is your mission to defeat as many enimies as possible in the time limit.
This comes from one of the previews that we saw where, for a split second, we see a clip of such a 2D shooter, but it's never shown how it is accessed, much less if it's even in the game to begin with. Gamexplain did a breakdown where they saw an arcade cabinet in the hub, which may be where we can access the game. As of now, we've yet to see the purpose of the 2D sprites we saw, much less if it's even playable.
A bunch of new stages got shown: There will be set of Super Mario Sunshine based stages like Delfino Plaza, Porto d’Oro or Monte Bianco.
This really falls into the "TOO GOOD TO BE TRUTH" category. Everyone's made jokes about how Splatoon carries similar vibes behind Mario Sunshine, to the point that even Nintendo has acknowledged it, and if it turns out to be truth, it wouldn't be surprising, but I seriously don't think Nintendo would be cool enough to pull it off (I'd love to be wrong though).
Battle Dojo will be also playable online.
Would surprise absolutely nobody.
Team Deathmatch mode announced.
Nintendo has mentioned there are more modes we've yet to see, and a basic team deathmatch wouldn't be completely out of the question, especially since the assets needed for one are all there. Wouldn't be surprising whatsoever if it has one, though I can bet you it won't be called Deathmatch (maybe Squidmatch, or Inkmatch).
campaign will be playable in different difficulty levels. Campaign features 28 levels with a total playtime of around 14h.
Here's where things start to sound like the person who wrote this is starting to guess how the campaign would work. 28 levels do sound reasonable, but something about the number 28 rubs me the wrong way.
if you mastered the campaign on hard difficulty, you’ll unlock Extra Hard mode: One hit, instant death.
I can see this happening. Nintendo has pointed out that they want to do something for the hardcore audience behind Splatoon. This is something I can get behind if this turns out to be an added feature.
Tournament mode announced: In this mode you can participate in monthly tournaments hosted by Nintendo or by other players.
Mario Kart 8 has tournament mode, Smash Bros. soon will, not so shocking if Splatoon had it. Another one of those educational guesses made by the "leaker".
Special promotion announced: If purchase the game on Nintendo eshop before July 31st, you can recieve a free download code for 1 out of 5 possible games.
Nintendo tends to do this every now and then with some of their newly released games. Wouldn't be surprising to see them do that again with Splatoon. It would definitely help make the game be much more notable as a result. Another educated guess.
The development team plans to release additional Downloadable content in the future. Nintendo plans to give us more information in the future.
Like with many other shooters out there, Splatoon's design is way open to the idea of DLC. It wouldn't be at all surprising.
Demo Version will be available on the Wii U eshop shortly after the presentation:
(1 Stage online, 1 stage Batlle Dojo, First Campaign level)
Everyone is begging for a demo. Seems like something the "leaker" put in to get everyone hyped. Chalk up this one in the "TOO GOOD TO BE TRUTH" category. I know the Wonderful 101 and Bayonetta 2 had a demo following their respective Direct, but that was Platinum Games' choice to do it. I've never seen Nintendo themselves release one of their demos following a Direct.