I'm just trying to help you with some additional information about webp:
For one, you don't need an online encoder for webp.
There's a webp plugin for Photoshop (I've never used it and I haven't used Photoshop for more than a decade, so I don't know how well it works), GIMP and some other tools:
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And there's a little image viewer named IrfanView that also has a very user friendly batch conversion functionality built in and supports webp (and a myriad of other media formats). It's quite comfy to use for png -> webp conversion in bulk. You'll need both - Irfanview program and its plugins.
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I'm not sure if you qualify as a non-commercial user, though.
XnConvert is probably at least as good and free of any restrictions, I've just never used it.
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(XnView is their image viewer:
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)
And you can reduce the size a lot more in webp lossy mode. You'd just have to experiment with the level of quality, so that the visible loss in quality would be as minimal as possible and acceptable to you.
But I do understand that you don't want to lose anything in quality and whatever you decide is totally fine with me. I don't have any capacity limits on my download and I don't mind downloading gigabytes of your game. :biggrin: