Mutation: starting to tighten this thing up

I had a couple productive playtests of Mutation yesterday, below is the feedback I received:

• Change removal rule to "Remove, then place. You can't place where you removed".  This is a far more elegant and simple rule to explain over the "only remove when adjacent to a chain of at least 2 dice" rule i've used for years.
• Variable end game condition, most likely first to 10 (value to be tested) or largest strain after 20 turns.
• Test a partner variant where you work together and win as a team when one of you has the longest strain.
• Work on 2 player game more.  
• Perhaps both players play two colors in much the same way a partnership game would play out.  
• Perhaps you roll four dice at a time (2 of each color) and place both on your turn.
• Asymmetric 2 player mode, one player is the bacteria and the other is an immune system or antibiotic fighting back. 
• Players have different actions available to them, bacteria spreads fast but the opponent is "Stronger" somehow.
• Tested some cardplay options. Nothing has really clicked yet, though I like the idea of a variant that uses card play to slightly modify dice and perhaps restrict double total numbers. 
• Tried 6 cards, one of each value, and you can spend them to induce a double or break the level 1 adjacency rule.
• Issues here are how it can slow down the game and potentially have odd stalemate moments where the first to spend the card will surely lose becasue the opponent can spend theres to come back and then both will lack the card and the second player will have the desired board position.

General consensus is that I DO have something here and it is close to done.  I just need to tighten up some of the rules, and increase the possible variant options to add value to the overall game.  There was also a feeling from everyone that Mutation isn't necessarily detracted by being a pure dice game.  I don't want potential customers to be turned off by the apparent lack of proprietary content.