I want to render my movies at 1200 x 1200. Can I do this using Houdini Indie ? In theory this is a lower resolution than 1920 x 1080. Does Houdini Indie limit the resolution based on total number of pixels or is it hard limited at 1080 vertical pixels which limits me at 1080 x 1080 square ?

I think you could only render @ 1080x1080. That is the limit of the Indie license.

That is too bad. Actually it should allow 1440 x 1440 square resolution which is the equivalent of 1920 x 1080 in total number of pixels. Both equals 2073600 pixels (Roughly 2 megapixels) on the other hand 1080 x 1080 is 1166400 pixels (only about 1 megapixel). I hope SideFX Software makes an improvement on this one.