First of all, thank you for your interest in this game. Response like yours are really uplifting my spirit to keep improving the game.
As for the future of the game, the longest shot would be adding fellow survivor AI, which can also be overridden by other player...
Then, I also want/need to update level graphics, especially on the city levels, adding path variation, small effects details etc...
And the nearest timeline would be adding more special zombies... I have made a Juggernaut which can pick and throw cars at player(spoiler :D), but I have to make special level for it since it tends to stuck on narrow passages due to it's size. It was planned to be shipped at the last update but due to that problem, I postponed it, maybe next update...
Also the special zombies that I've yet but urgently want to make is the blood witch, which basically all other special zombies combined into one package...
Also, from the reviews on the play store, people want an actual story... I think I'll have to make separate games for that :)
Well... that said, currently, I'm still focus on working on another game which I'd like to finish before IMGA global which is less than 3 months to due :)