Wow, my prediction about comparing this to Project Diva series is right. It appears that the close to this game is likely to be Project Diva series judging from the PV video I already saw. There are two videos so far but they are actually the first PV videos in two versions.
There will be in-game 3D graphics sort of music videos as well as the anime style music videos representing the game franchise. Divided into few kinds of music videos are, anime style, band style, live style and drama style. For anime style, there will be scenes taken from the anime based on the game franchise. The band style may be interesting to compete with another rhythm game based on the rock band anime on the PSP which is done by the creators of Project Diva series. Interestingly enough, the idols are dressed up in the performance outfits for band performance in addition to performing other stuffs on stage and other locations which may make the entire game the competitor to Project Diva series. The drama style, well, I don’t even know what to say but it seems that this style of music video is also in other rhythm games as well.
Other than four styles of music videos, there will be true rhythm gameplay that is taking place on all music videos. Like Project Diva series, try not to screw up. Lastly, this is what the Idolmaster game can be in the arcades as it makes proper sense in terms of gameplay.