Nice game!
Some bugs:
1) Plagueflies tooltip says +2 plague, where the effect is actually +3.
2) Diversion tooltip says requires 3 supply, but you can play it with less, even 0 supply.

In layman terms, Floor cuts all the decimal rubbish off the end. Sometimes called truncation.

examples:
floor(3.14159) returns 3
floor(4.99999998) returns 4
floor(5) returns 5

Interesting. I hadn't thought of doing that. I just implemented it and I have to agree, the levels are now far easier to edit by hand. The only potential pitfall is that it's now harder to have more than 36 tiles in a tileset. I hope that won't be a problem in the project I'm using it for. It can b...

spirulence, if you use lua's double square bracket notation for strings, then you can get a nicer looking way to represent your levels: local level = [[ ........................ ........................ ........................ ........................ ....................1111 .........................