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+# Moonfall
+
+Moonfall is the name of a game engine that I spent several months developing back in 2008. It leveraged
+[SDL](https://www.libsdl.org/) for graphics, [Lua](http://www.lua.org/) for in-game scripting, and
+[wxWidgets](https://www.wxwidgets.org/) for the built-in developer tools. The cross-platform engine was written using
+[Code::Blocks](http://www.codeblocks.org/) IDE, but Visual Studio project files are also available.
+
+The inspiration for the game came partially from the [Harvest
+Moon](http://en.wikipedia.org/wiki/Harvest_Moon_%28video_game%29) video game for the Super Nintendo and from the [When
+They Cry](http://en.wikipedia.org/wiki/Higurashi_When_They_Cry) by [07th
+Expansion](http://en.wikipedia.org/wiki/07th_Expansion). The protagonist is a city dweller, who upon inheriting a small
+farm from a distant relative decides to try his hand in agriculture. He finds the residents of the nearby small town a
+friendly bunch, but something about them does not seem right. Everyone is appears to be hiding something from the
+player, who must uncover the truth to survive. In short, this is (as I have described it to my friends), "Harvest Moon
+with murder."
+
+From a technical point of view, the game engine was an exercise in creating a completely data driven game. In
+retrospect, it was probably over-engineered, but in general it was flexible and I liked what I could do with it. At the
+core of the engine was the `Actor` class, the functionality of which could be expanded through add-on properties. The
+property definitions were specified in XML; for example, below is the definition for the playable character:
+
+
+```
+<Actor alias = "Player.01" dynamic = "1" layer = "4" thumbnail = "Player.01.Idle.S.01">
+    <Properties>
+        <Animation />
+        <Script resource = "Player.01.Default" />
+        <Physics />
+    </Properties>
+</Actor>
+```
+
+In addition to the self-explainable `Animation` and `Physics` properties, you can see a `Script` node which associates a
+Lua script with the actor. Scripts would get notifications about events such as `OnActorUpdate`, during which custom
+processing could take place:
+
+
+```
+function OnActorUpdate(elapsed)
+    if InputIsKeyTriggered(META_KEY_USE) then
+        DoActorUse()
+        return
+    elseif InputIsKeyPressed(META_KEY_UP) then
+        DoActorWalk(DIRECTION_NORTH)
+        return
+    elseif InputIsKeyPressed(META_KEY_DOWN) then
+        DoActorWalk(DIRECTION_SOUTH)
+        return
+    elseif InputIsKeyPressed(META_KEY_LEFT) then
+        DoActorWalk(DIRECTION_WEST)
+        return
+    elseif InputIsKeyPressed(META_KEY_RIGHT) then
+        DoActorWalk(DIRECTION_EAST)
+        return
+    end
+
+    DoActorIdle(playerDirection)
+end
+```
+
+Scripts can directly interact with properties on the parent `Actor` and can communicate with surrounding world via a
+messaging system. This made it possible to build any game object imaginable by editing a couple of XML files and some
+simple scripting.
+
+
+```
+function DoActorWalk(direction)
+    if playerAction == ACTION_WALK and playerDirection == direction then
+        return
+    end
+
+    ActorPhysicsSetVelocity(playerId, playerWalkVelocities[direction])
+    ActorAnimationSet(playerId, playerWalkAnimations[direction])
+    ActorAnimationPlay(playerId, true)
+
+    playerDirection = direction
+    playerAction = ACTION_WALK
+end
+
+function DoActorUse()
+    actorsIds = ActorPhysicsQueryShapeCollisions(
+        playerId,
+        ACTOR_SHAPE_TYPE_COLLISION_INTERACT
+    )
+
+    for i, v in ipairs(actorsIds) do
+        ActorScriptSendMessage(v, "interact", { user = playerId })
+    end
+end
+
+```
+
+I eventually stopped work on Moonfall due to a lack of time, combined with the fact that I am not an artist and could
+not author the assets required to develop this into a complete game. The full [source
+code](https://github.com/FooSoft/moonfall) is available on GitHub; below are some screenshots of the game and built-in
+tools.
+
+## Screenshots ##
+
+![](index/gameplay.png)
+
+![](index/sprite_editor.png)