The 'Production Line' video below has apparently detailed some upcoming updates and plans for the Collection:
Should've launched in a better state, of course, but kudos to them for plugging away at sorting the issues post-launch.
From the summary I read (the video is in Japanese) it sounds like they teased an upcoming, larger scale event with a focus on new projects.
Volume 2, perhaps?
I was in that boat a few days ago too. Played a bit more and taking hints from here about going after one weapon and upgrading, trying to get as many coins in a game I managed to upgrade a few items. Not sure if I just got better or if the Library level is just easy but get that unlocked. First time I played it I got to about 25 minutes and think I maxed out all my weapons. Racked up like 2,000 coins in the game too as I got some coin shower thing where killing enemies gave me coins. Played a couple more games and both time got to the 30 minute mark, I’m assuming what happens when you get there in unavoidable on normal levels. But each time I had all weapons maxed and was getting a bag of coins per level up which was like every 10 seconds, Garlic, Bible books and the healing item make it seem like you’re invincible.
I think I’ll pay the £3.39 for this as it does make for a good hour time waster (yesterday I had wasted two hours just like that.)