Sad news. No Idolmaster shown in TGS...sorta. I guess there's a Katamari Demo so maybe you can play Saki's song.

There will be a Asobi store branch where they'll sell GK goods. It's kinda funny it says "We will be selling goods from titles shown on the floor...and Gakuen Idolmaster". Wouldn't be surprised if this is just a Katamari Saki or something.

https://tgs2025.bandainamcoent.co.jp/jp/