I think this is "right". I can understand, for a competitive multiplayer game, that you want to eliminate randomness in large quantities. But this is not a competitive multiplayer game. Randomness means variety, and variety is good.

If I remember correctly, there's a tag in ElementalDefs that presents a bottom limit to how many techs will be displayed ("display at least this many techs, regardless of rarity"). I think that could be used to make sure the user can always choose important things, but not necessarily the things he wanted (you don't want to end up in a situation where the player has only bad choices).

Lovely Idea.

I support it wholesale.

I agree.  In fact, I would piggy back (froggy-back?) on the above ideas by suggesting that some rare, very rare, unique technologies, or 'one time construction projects / weapon - armor making / spelling result from exploring and researching in a lost library / temple.  If you have your people working a library, there is a small chance they will 'discover' something valuable from the past.

And, may I suggest that the 'new' discoveries sometimes have an 'up' side as well as a 'down' side?

Looks good - agree with all of this - one question - how much of this could be done through the existing structure by way of a modified tech tree?

consider the following example - normal leather armour is a prerequisite for metal armour

you might for example have something like 20% chance that you get metal armour before leather armour - this could be crude metal armout that either

• takes more resources
• limits the mobility more than standard metal armour
• is a bit worse than normal metal
• adds some other penalty (training time)

the normal metal armour could have as a prerequisite either leather or crude metal

It would be nice if the pre req techs or other stuff could add to the chance that certain techs appear e.g. metal armour have 1% chance of happening naturally, +5% with metal weapons, +10% with leather armour, +15% with crude metal armour, +5% if you have a mine in your empire, +5% if you have a forge, +5% if you have a fire shard etc.

Sword of the Stars had a frustratingly awesome random research set up. "Please great Carl Sagan in the sky let phasers unlock after this." If they didn't it was set up so another research would have another chance to unlock them. Games were vastly different each time because of that. If I remember, you could even set up special missions to teach a tech to some one else if they didn't unlock it in their tree.