Works pretty well, well done! Can you finish the stone structure? Seems to not be working for me.

Apart from having more content, I think the game could use a couple of UX improvements:

• Progress bars are barely visible, maybe use a different color?
• If you want to keep using arrow keys for rotation, why not use them to set an absolute orientation?
• Make it possible to delete placed (or even built) conveyors.
• In the long term, an in-game tutorial would be nice, though you probably want to wait until you've finished your systems before adding that.
• Maybe add markers where you can get different materials. Had a bit of trouble to find the correct spot to gather wood.
• Maybe add different zoom levels. Not necessarily continous zoom levels if you want to keep this sort of retro style, but maybe a x2 zoom level would be nice for the more finicky operations.

Visually, it looks fine, but also a little too generic for my taste. Maybe having the bird sprites stand out a little more would be a good idea. Also, I'd love some animation in those water tiles.