Kruelgor no longer posts on these forums. His scenario is complete, but he has since stopped working on it (check the 2K forums). I believe its development has shifted over to someone else.
This is an easy fix. There are two ways of doing this; The easy (read: messy), and the hard (read: clean) way of doing this.
Easy way:
Code:
<GameData>
<Technologies>
<Update>
<Where Era="ERA_RENAISSANCE"/>
<Set>
<Disable>1</Disable>
</Set>
</Update>
<Update>
<Where Era="ERA_INDUSTRIAL"/>
<Set>
<Disable>1</Disable>
</Set>
</Update>
<Update>
<Where Era="ERA_MODERN"/>
<Set>
<Disable>1</Disable>
</Set>
</Update>
<Update>
<Where Era="ERA_FUTURE"/>
<Set>
<Disable>1</Disable>
</Set>
</Update>
</Technologies>
</GameData>
This will disable all techs after Medieval, stopping the game's tech progression there. I don't know if Disable is 0 or 1, or true or false. You'd have to experiment.
Hard way:
1) Delete all of the renaissance, industrial, modern, and future techs (minus the future tech).
2) Move Future Tech to in front of the medieval techs, and make those medieval techs the prereqs to Future Tech.
3) Delete all units/buildings/projects past the Medieval Era. You may want to increase tech costs to immerse yourselves in the earlier age.
This has the same effect as the steps above, without the red techs and unnecessarily long tech tree + civilopedia assets.
Good luck!