Oh I misread. I think the reason why the latest version isn’t free is that there isn’t much new content. If you want to know what the new content is: . .
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. A bit of spoiler:
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. There is only a short bossfight. Most of the extra content are just cutscene. And I believe the update is mostly just to complete the game and add the remaining 4 game over animation (which are certainly won’t be available in free version). So apart from the short bossfight and some game over animations, you aren’t missing out much