so is there a completed tool or full source to convert the images? Not yet. I started the research ages ago with a Lazarus project. Currently it's a huge block of Pascal code with hard-coded search paths and a lot of useless testing stuff :) But, as soon as I have some spare time, I will publish a ...

[...] those Snowhead_Ent_Spike_0x ones look a little strange at the bottom [...] Have seen it, yes. But all other rgb5a3 images (with and without alpha) look fine, so I classified it as data error/corruption. ps: note that the US_doorway2.T64 is the only file that has the game id "NZLP" (...

Second attachment...

It's a bit more complicated since the image files are stored in 8 different formats... vc64_t64_head { uint8_t magic[4]; // "VC64" uint8_t game_id[4]; // "CZLE", "NZLP", "NZSE" uint32_t _0008; uint32_t width; uint32_t height; uint32_t _0014; // 0, 1, 2 uint32_...