Ultima5Redux VS OpenLara

Ultima IV + V + VI - Install Ultima 5 Redux for Ultima V. Use ScummVM for Ultima VI.

Ultima 4+5+6 - Install Ultima 5 Redux if you want some quality of life improvements and bugfixes, Ultima 5 Redux is an open soure re-implementation project. Use ScummVM for Ultima VI.

Ultima5Redux - Ultima V

The code is actually open source and found here: https://github.com/bradhannah/Ultima5Redux/blob/master/Ultima5Redux/MapUnits/CombatMapUnits/CombatMapUnit.cs

I didn't notice anything suspicious in his explanation of how the AI works, though he glosses over navigation. I assume he is using the OpenLara engine, in which case he easily has access to level geometry or other parts of the game at runtime that would normally be inaccessible. However when watching the AI play, I got the impression there was two much overlap between what the AI does and says. For example, based upon what I understand of the explanation of how the AI works, the part playing and the part talking are not interacting with each-other. Voice lines are simply generated based upon what is on screen and there is no true common intent behind the AI's actions and speech. This makes me suspect the entire video is simply a scripted imitation of AI.

You can try source engine ports like xash3d diii4a Serious Sam Freedoom OpenLara Quad Touch and Source Engine

It is, it’s the OpenLara engine, so it’s running native code rather than emulating the PSX version.

OpenLara

You can play it online here, the github link on the page also has a downloadable version that plays offline and works with the controller. http://xproger.info/projects/OpenLara/