diff --git a/ly-core/build.zig b/ly-core/build.zig
index 37b8668..2dd9725 100644
--- a/ly-core/build.zig
+++ b/ly-core/build.zig
@@ -24,7 +24,7 @@ pub fn build(b: *std.Build) void {
     const zlua = b.dependency("zlua", .{
         .target = target,
         .optimize = optimize,
-        .lang = .luajit,
+        .lang = .lua53,
     });
     mod.addImport("zlua", zlua.module("zlua"));
 
diff --git a/ly-core/src/root.zig b/ly-core/src/root.zig
index 6df7592..26b5f57 100644
--- a/ly-core/src/root.zig
+++ b/ly-core/src/root.zig
@@ -172,17 +172,54 @@ pub fn LuaParser(comptime Struct: type) type {
                 return;
             }
 
+            // handle missing required fields
+            if (lua.isNil(-1)) {
+                return;
+            }
+            const actual_type_info = @typeInfo(actual_type);
             // dispatch depending on type
-            if (type_info == .int) {
-                const value = try lua.toInteger(-1);
-                @field(data, field.name) = @intCast(value);
-            } else if (type_info == .float) { // all floats
+            if (actual_type_info == .int and is_optional) {
+                if (lua.isInteger(-1)) {
+                    const value = try lua.toInteger(-1);
+                    @field(data, field.name) = @intCast(value);
+                } else {
+                    const str = try lua.toString(-1);
+
+                    var view = try std.unicode.Utf8View.init(str);
+                    var iter = view.iterator();
+
+                    const codepoint = iter.nextCodepoint();
+
+                    if (iter.nextCodepoint() != null)
+                        return error.ExpectedSingleCharacter;
+
+                    @field(data, field.name) = if (codepoint) |cp| @intCast(cp) else null;
+                }
+                // non null integer
+            } else if (actual_type_info == .int) {
+                if (lua.isInteger(-1)) {
+                    const value = try lua.toInteger(-1);
+                    @field(data, field.name) = @intCast(value);
+                } else {
+                    const str = try lua.toString(-1);
+
+                    var view = try std.unicode.Utf8View.init(str);
+                    var iter = view.iterator();
+
+                    const codepoint = iter.nextCodepoint() orelse return error.EmptyString;
+
+                    if (iter.nextCodepoint() != null)
+                        return error.ExpectedSingleCharacter;
+
+                    @field(data, field.name) = @intCast(codepoint);
+                }
+            } else if (actual_type_info == .float) { // all floats
                 const value = try lua.toNumber(-1);
                 @field(data, field.name) = @floatCast(value);
-            } else if (type_info == .bool) {
+            } else if (actual_type_info == .bool) {
                 const value = lua.toBoolean(-1);
                 @field(data, field.name) = value;
-            } else if (field.type == []const u8 or field.type == [:0]const u8) {
+            } else if (actual_type == []const u8 or actual_type == [:0]const u8) {
                 const value = try lua.toString(-1);
                 if (actual_type == []const u8) {
                     const duped = try allocator.dupe(u8, value);
@@ -191,7 +228,7 @@ pub fn LuaParser(comptime Struct: type) type {
                     const duped = try allocator.dupeSentinel(u8, value, 0);
                     @field(data, field.name) = duped;
                 }
-            } else if (type_info == .@"enum") {
+            } else if (actual_type_info == .@"enum") {
                 const value = try lua.toString(-1);
                 const variant = std.meta.stringToEnum(actual_type, value) orelse return error.InvalidVariant;
                 @field(data, field.name) = variant;
diff --git a/src/main.zig b/src/main.zig
index f74844d..e2c12d5 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -238,7 +238,7 @@ pub fn main(init: std.process.Init) !void {
     };
 
     // TODO do not hardcode config file name
-    const config_path = try std.Io.Dir.path.join(state.allocator, &[_][]const u8{ config_parent_path, "config.ini" });
+    const config_path = try std.Io.Dir.path.join(state.allocator, &[_][]const u8{ config_parent_path, "config.lua" });
     defer state.allocator.free(config_path);
 
     custom.binds = .empty;
@@ -274,6 +274,7 @@ pub fn main(init: std.process.Init) !void {
     };
 
     state.config = config_parser.structure();
+    std.debug.print("=== {}\n", .{state.config.gameoflife_fg});
 
     var lang_buffer: [16]u8 = undefined;
     const lang_file = try std.fmt.bufPrint(&lang_buffer, "{s}.ini", .{state.config.lang});