Keyboard shortcuts:
WASD moves the tilesheet around
Left-Mouse button interacts with the tilesheet and the map
Z decreases the layer
X increases the layer
H hides the currently-selected layer
G toggles the grid
E selects the eraser tool
P selects the pencil tool
B selects the bucket tool (HAVEN'T IMPLEMENTED YET)
I toggles this help box

The app will keep track of used layers; try selecting them from the dropdown at the bottom!

Layers determine draw order. Lower numbers (negatives are allowed!) will be drawn before higher numbers. If a tile is placed on Layer 0 and another on Layer 1, then the tile on Layer 1 will appear on top of the tile on Layer 0.