A great entry. A few tweaks (like the arrow issue), a few more variations and upgrades etc, and this would be even better! 

I played it by myself but I like the idea of taking over the body slowly and competing with another player. What I did notice is that the arrows were sometimes hard to tell which direction it was pointing to, so I made a few mistakes. Other than that, it looks like a fun competitive game to play with friends.

Yeah only had myself so I just controlled one of them, I agree the arrows need stems or something to make it clearer which you were supposed to push. However I think this would be quite a good party game. Especially with a controller which naturally has the four buttons you'd need.

Thanks everyone for the comments!

The hard to see arrows - which everyone rightfully has a problem with - are an unfortunate effect of the 3D text in Unity refusing to render most non-Ascii characters. I put something that worked and didn't have time to replace them with images of better Unicode arrows.

Fun game! managed to infect a whole leg, but definitely struggled to tell which way the arrows were pointing sometimes (especially when under time pressure!) Might be worth adding a "tail" to the arrows to make it really clear 

This is a cute idea. I could see it working well as a frantic party game - though on my play throughs it moved kind of slowly - mostly because we couldn't read the arrows! (I'd definitely re-do those)

It looks good, and visualising the four viruses with colours filling from each part of the body is great. Update us if you rebalance it so we have any hope of filling the body :D

I like the concept and the visuals showing the spread of the virus around the human. It felt engaging as I was playing against the clock, but I found it too hard to beat! Though I can see that it would be easier with multiple players, I could only play it alone. Also as others have mentioned sometimes the arrows were diagonal, it was quite confusing when this happened.

I felt like I couldn't play this properly (couldn't do multiplayer), but the mechanic was really good.  I too had the "left/right arrows sometimes look diagonal" thing, but hopefully that would easy to fix in future if you so desired. It was hard but seemed to work really well - I particularly liked the chalk outline; I'd love to know what happens if you completely fill it!

The human immune system is an amazing thing, and that's never been clearer to me than trying to win against it single-player using two hands. It's amazing how uplifting it can be to lose!

(Not sure if the arrows are intentionally hard to differentiate, but my brain kept trying to think of the "right" and "left" arrows as pointing diagonally upwards.)