If castaway 3 is ever made, a nice feature would be to toggle on/off exp sharing with your pet, so you can make a new pet level up faster, or get your character to a higher level more easily.
Run doesn't use any mana or energy, so why have a run button at all? The character should be running all the time, instead of it being something I have to toggle each time I load my game.
The problem with the 'greedy bastard' skill is that each successive point makes it cost 2% less to build a tower than it did before, so each skill point does less and less. This means for example that the pistol tower only costs 2 less than it did before, while the barricade remained the same. Maybe you could change that to a higher % or set amount?
Well, I managed to break the game by accidentally clicking the map too fast more than once, making all arrows to change scenes turn into the hand cursor and me unable to use my map, despite reloading the game. Whoops.
I found that even with the tutorial the interface was overly complicated, having to spend so many Kreds to get worthwhile equipment was very off-putting. An alright concept, but many improvements could be made.