The tech are cool

and I have two suggestions:
- put the icons (and preview) in the game size, large icon is 128x128 and small icon is 32x32 pixels, I think. Do not forget to change to 8 bits color.
- suggest a little text to the icons
Maybe the Monster-Pig could be "mutation" tech

The last one, I really enjoy it, it is the best, the image is very good

Keep going growing Gelven!!! BTW, how about the Europe conquest scenario?