Thanks for feedback! We will consider reducing the minimum size in the next release. We are also working on a dual pc solution (sever/client). Which shapes do you want to add? My personal opinion is that coplex shapes will be too much distracting.
The overlay you saw on some videos is an old one from SteelSeries. It has noticable latency for all the static shapes (“heart” etc), no settings for filtering, trail or size and it only works with SteelSeries Sentry eye tracker, so personally I would recommend using Tobii Streaming Gaze Overlay instead.