Добавил простую обработку мыши с учётом масштаба

game/main.lua

@@ -47,6 +47,48 @@ function love.load()
         16 * 5
     )
     tilemap:random(10, 10)
+
+end
+
+-- 0: nothing
+-- 1: holding LMB
+-- 2: dragging with LMB held
+local mouseState = 0
+local mouseStartX = 0
+local mouseStartY = 0
+local mouseEndX = 0
+local mouseEndY = 0
+
+function love.mousepressed(x, y, button)
+    if button == 1 then
+        if mouseState == 0 then
+            mouseState = 1
+            mouseStartX = x
+            mouseStartY = y
+        end
+    end
+end
+
+function love.mousemoved(x, y, dx, dy)
+    if mouseState == 1 then
+        mouseState = 2
+    end
+    -- fallthrough
+    if mouseState == 2 then
+        mouseEndX = x
+        mouseEndY = y
+    end
+end
+
+function love.mousereleased(x, y, button)
+    if button == 1 then
+        if mouseState == 1 then
+            -- TODO: callback
+        elseif mouseState == 2 then
+            -- TODO: callback
+        end
+        mouseState = 0
+    end
 end
 
 function love.update(dt)
@@ -84,6 +126,12 @@ function love.draw()
 
     drawText('Hellorld!', 160, 100)
 
+    if mouseState == 2 then
+        love.graphics.setColor(0, 255, 255)
+        love.graphics.rectangle("line", mouseStartX, mouseStartY, mouseEndX - mouseStartX, mouseEndY - mouseStartY)
+        love.graphics.setColor(255, 255, 255)
+    end
+
     love.graphics.draw(hamsterMouse, love.mouse.getX(), love.mouse.getY())
 
     platform.drawEnd()