Think it was v4.

which one os ur floor mod in this image?

This lead to another fun fact mentioned in the book as the developers all played on a different screen resolutions and monitor sizes, when the chief art designer Harter Ryan ordered them all to play on 800x600 to get the size of units and buildings correct for each stage of production from then on relatively correct. That process took 2 weeks then they could decide whether or not certain graphics had to be redone. Example are the Pre-Release Screen in Gaming Magazines at the time that offered overdimensional Castles 4 times the width of actual release.
If you play the leaked Alpha version you can make up some of the noticable differences that were fixed later on.

Hence I remember the days where I had to get the voodoo for 3D and another for 2D, and the S3 utterly underperforming with driver madness. Then went to nVidia when 3dfx vanished, had one ATi 9600 Pro in between but overall the drivers are better and the longevity of cards are more reasonable now then the late 90s, 6 month span of a new GFX card due to slow speeds, malfunction, driver incompablities, lack of features or feature invention.

Actually they were quite ahead of their time with all the features that were considered to be added, the economy system was subject to be the same depth as Sid Meier's Civilisation but with a more hardware hungry and state of the art RTS game at hand compared to at the time round based text based games or even the early 3D games of the time. To me they tried to offer the Depth and Historical Backround of Civilisation and the modern technology playability of RTS ala Command and Conquer. The 90s were quite more challenging for the devs as there were much more companies around that each offered some unique techniques on their cards as compared to todays Big 2, nVidia and ATi/AMD. Back then S3, ATi Rage, Rendition Verite, 3dfx Voodoo, Matrox G Series, Intel GMA, nVidia NV Series and PowerVR Kyro.

Ensemble Studios Official Strategies & Secrets to Microsoft Age of Empires II The Age of Kings by Bruce C. Shelley and his merry men published by Sybex Inc in 1999.
Chapter 13 The Making of Age of Empires II - a small excerpt from our list of AoK-Features which weren't taken over in the Game.

- Unit- and formation-confrontation
- Mercenaries
- Crests
- Pirate-Civilisations
- Trading from outside the map
- Outlaws
- Renewable resources
- Damage from fire in devastated buildings
- Trading-Goods
- Streets (buildable)
- Pillage of resources
- Fith ressource (ore)

Don't have any sources. In fact I didn't think of that fact when doing the mines.
But iron is a very obvious resource for this game.

How do you know iron was a fifth ressource in AoE2? Do you have sources? Sounds very interesting.

Would have been really cool - one more reason for new/really updated versions of great old games...

Like with 'settlers next generation', not like 'AoE2'...^^

actually ore was the fith ressource that just didn't make it further into development for AoE2, they would have used it for forge upgrades but they would then go for gold. I would have welcomed it to be used for proper use in the game. Same for Gold which would have been used to buy land for off map market trading like in Stronghold / Battle for Middle Earth where you expand kingdoms. However AoE2 was just too early for those kind of programming.