What was the main learning you got from building the engine? Was there some feature you wanted that no other engine at the time had? If you built an engine today, what would you do differently?

I thought most of the existing engines out there were too complicated, so I wanted it to be easy to use. Probably that's also why it became that popular.

For a modern engine today - I think the architecture of the engine would look different - and would focus more on creating and organizing content then mostly on rendering.

I was involved in 3D back then wenn Irrlicht & Co had some traction:

Todays graphics engine look completely different than the first flexibel pipelines around 2002-2005, and the rise of AI for usage during rendering will change the tech paradigms further (for the younger ones: In 2001, NVidia announced the Geforce1, we had 1 pixel shader and 1 vertex shader :-D LOL)

Thank you for doing it ! What was the motivation behind it/when did you start building it ?

I never built anything with it but reading through the source code got me to learn so much about programming. I probably spent more time copying stuff from Irrlicht/Ogre3D/ODE (although I never managed to grok that one) than anything else in high school.

I originally wanted to create a 3D game - and needed an engine for it. Never made it to the 3D game part, though :)

Many such cases

I spent a lot of time studying this code way back when, it was a valuable resource in my personal journey, so thank you x1000!

Thanks for the quality software. Had some good times in high school trying out Irrlicht

It was a great engine. You built a great piece of software.

An old gamedev teammate sent me this link - got hit with a wave of nostalgia. Big thanks for creating Irrlicht back in the day.