A Gem of a Game... aheh...
Definitly one of the best of the "tower defense" style games out there. The gem crafting itself is neat and simple. But takes some thought to get to the better gems. The monsters have some small diversity. Though they could use a little more variety really. The upgrade system is pretty good and allows a player to customize the effects to suite preffrences.
Heres some tips for reaching the latter levels.
1: Put points into increasing your mana total. More mana means more gems or towers can be set up early.
2: put points into starter gems, and definitly aim to max out the final skill of high grade gems as this saves you thousands in MP. Grab the medium grade gem upgrade too as then you can usually merge enough gems to have a really good start.
3: work on maxing out pure gem mastery and then follow up with dual gem. On the side put points into lowering the cost of towers, pits, and gem costs.
4: During play the first things to do is increase your mana buffer as this increases the mana gained per kill. At the high end of upgrading ths it really pays off for some of the longer battles. Keep your toweres relatively clustered together and make sure you have at least 4 pits lined up before the first runners get out the gate.
5: Allways make sure you have a buffer of mana to cover any potential stragglers that make it through your gauntlet.
6: For the final battle it is vital to keep a stockpile of at least 15k mana. The final boss is MEAN! Make sure you have as many towers upgraded to 8 as you can!
Great game and looking forward to the sequel some day!