diff --git a/jsconfig.json b/jsconfig.json
index c24ac80..f9b29f6 100644
--- a/jsconfig.json
+++ b/jsconfig.json
@@ -1,5 +1,8 @@
 {
 	"compilerOptions": {
-		"target": "ESNext"
+		"target": "ESNext",
+		"noImplicitAny": true,
+		"checkJs": true,
+		"strict": true
 	}
 }
diff --git a/source/data_asset_generator.py b/source/data_asset_generator.py
index 88d575f..b8044e8 100755
--- a/source/data_asset_generator.py
+++ b/source/data_asset_generator.py
@@ -1,7 +1,6 @@
 #!/usr/bin/env python3
 import argparse
 from pathlib import Path
-from PIL import Image
 
 parser = argparse.ArgumentParser()
 parser.add_argument("input")
@@ -34,9 +33,11 @@ def generate_data():
 def generate_hashmap_init():
 	string_list = list()
 	for index, data in enumerate(file_array):
-		string_list.append(f"if (strcmp(filename, \"{data["filename"]}\") == 0) {{ *data = &data{index}; *size = sizeof(data{index}); return 1; }}")
+		filename = '"' + data["filename"] + '"'
+		string_list.append(f"if (strcmp(filename, {filename}) == 0) {{ *data = &data{index}; *size = sizeof(data{index}); return 1; }}")
+	strings = '\n'.join(string_list)
 	return f"""int get_file_pointer(const char* filename, void ** data, size_t * size) {{
-{'\n'.join(string_list)}
+{strings}
 return 0;
 }}"""
 
diff --git a/source/game.js b/source/game.js
index 9d2da69..5486f29 100644
--- a/source/game.js
+++ b/source/game.js
@@ -9,6 +9,19 @@ const TERMINAL_VELOCITY_SPEED = 500;
 const PIPE_SPAWN_TIME = 4;
 const PIPE_MAX_TIME = 5;
 
+/**
+ * throws if input is nullish.
+ * @template T
+ * @param {T | null | undefined} value
+ * @returns {T}
+ */
+function nonNull(value) {
+	if (value == null) {
+		throw new Error("unexpected " + (value === null ? 'null' : 'undefined'))
+	}
+	return value
+}
+
 /**
  * clamps a number to the min and max values.
  * @param {number} num 
@@ -20,25 +33,31 @@ function clamp(num, min, max) {
 	return Math.min(Math.max(num, min), max);
 }
 
+/**
+ * picks a random number between the min and max values.
+ * @param {number} min 
+ * @param {number} max 
+ * @returns a random number
+ */
 function random_range(min, max) {
 	const minCeiled = Math.ceil(min);
 	const maxFloored = Math.floor(max);
 	return Math.floor(Math.random() * (maxFloored - minCeiled) + minCeiled);
 }
 
-/** @type {GRRLibTexture} */
+/** @type {GRRLibTexture | null} */
 globalThis.background = null;
 
-/** @type {DrawableObject} */
+/** @type {{velocity: number, position: number, texture?: GRRLibTexture}} */
 globalThis.bird = {
 	velocity: 0,
 	position: 0
 };
 
-/** @type {GRRLibTexture} */
+/** @type {GRRLibTexture | null} */
 globalThis.pipe = null;
 
-/** @type {GRRLibTexture} */
+/** @type {GRRLibTexture | null} */
 globalThis.pipe_flipped = null;
 
 /** @type {Pipe[]} */
@@ -63,16 +82,16 @@ function update_bird() {
 	const deltatime = wii.get_deltatime();
 	bird.position -= bird.velocity * deltatime;
 	bird.velocity = clamp(bird.velocity - (FALLING_SPEED * deltatime), -TERMINAL_VELOCITY_SPEED, TERMINAL_VELOCITY_SPEED);
-	
-	wii.grrlib.draw_img(0, bird.position, bird.texture, 0, 1, 1, WHITE_COLOR);
+
+	wii.grrlib.draw_img(0, bird.position, nonNull(bird.texture), 0, 1, 1, WHITE_COLOR);
 }
 
 function create_pipe() {
 	const top_max = 200;
 	const top_y = random_range(0, top_max);
 
-	wii.grrlib.draw_img(100, -top_y, pipe_flipped, 0, 1, 1, WHITE_COLOR);
-	wii.grrlib.draw_img(100, top_y + 400, pipe, 0, 1, 1, WHITE_COLOR);
+	wii.grrlib.draw_img(100, -top_y, nonNull(pipe_flipped), 0, 1, 1, WHITE_COLOR);
+	wii.grrlib.draw_img(100, top_y + 400, nonNull(pipe), 0, 1, 1, WHITE_COLOR);
 
 	return {
 		top_y: -top_y,
@@ -91,8 +110,8 @@ function update_pipe(pipe) {
 		pipes.splice(index, -1);
 		return;
 	}
-	wii.grrlib.draw_img(pipe.position, pipe.top_y, pipe_flipped, 0, 1, 1, WHITE_COLOR);
-	wii.grrlib.draw_img(pipe.position, pipe.bottom_y, globalThis.pipe, 0, 1, 1, WHITE_COLOR);
+	wii.grrlib.draw_img(pipe.position, pipe.top_y, nonNull(pipe_flipped), 0, 1, 1, WHITE_COLOR);
+	wii.grrlib.draw_img(pipe.position, pipe.bottom_y, nonNull(globalThis.pipe), 0, 1, 1, WHITE_COLOR);
 	pipe.position -= 100 * wii.get_deltatime();
 	pipe.time_active += wii.get_deltatime();
 }
@@ -110,18 +129,18 @@ function update() {
 	}
 
 	if (timer >= PIPE_SPAWN_TIME) {
-		timer = 0;
+		globalThis.timer = 0;
 	}
 
 	if (timer == 0) {
 		pipes.push(create_pipe());
 	}
 
-	wii.grrlib.draw_img(0, 0, background, 0, 1, 1, WHITE_COLOR);
+	wii.grrlib.draw_img(0, 0, nonNull(background), 0, 1, 1, WHITE_COLOR);
 	update_bird();
 	for (var i = 0; i < pipes.length; i++) {
 		update_pipe(pipes[i]);
 	}
 	wii.print("deltatime: " + wii.get_deltatime())
-	timer += wii.get_deltatime();
+	globalThis.timer += wii.get_deltatime();
 }
diff --git a/types.d.ts b/types.d.ts
index 064f9ff..d7a9d1e 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -1,9 +1,12 @@
-declare interface RGBA {}
-declare interface FilePtr {}
-declare interface GRRLibTexture {}
-declare interface DrawableObject {
-	texture: GRRLibTexture
-};
+declare interface RGBA {
+	__brand: "RGBA"
+}
+declare interface FilePtr {
+	__brand: "FilePtr"
+}
+declare interface GRRLibTexture {
+	__brand: "GRRLibTexture"
+}
 declare interface Pipe {
 	top_y: number
 	bottom_y: number
@@ -12,17 +15,20 @@ declare interface Pipe {
 };
 
 declare namespace wii {
+	function print(message: string): void
 	function exit(): void
-	function get_file(filename: string) : FilePtr
-	function get_deltatime() : number
-	function compare_rgba(color1: RGBA, color2: RGBA) : boolean
-	function print(message: string) : void
-	function rgba(r: number, g: number, b: number, a: number): RGBA
-	namespace grrlib {
-		function load_texture(file: FilePtr) : GRRLibTexture
-		function fill_screen(color: RGBA): void
-		function draw_img(xPos: number, yPos: number, texture: GRRLibTexture, degrees: number, scaleX: number, scaleY: number, color: RGBA) : void
-		function rectangle(x: number, y: number, width: number, height: number, color: RGBA, filled: bool) : void
+	namespace pad {
+		function buttons_down(): number
 	}
+	namespace grrlib {
+		function load_texture(file: FilePtr): GRRLibTexture
+		function fill_screen(color: RGBA): void
+		function draw_img(xPos: number, yPos: number, texture: GRRLibTexture, degrees: number, scaleX: number, scaleY: number, color: RGBA): void
+		function rectangle(x: number, y: number, width: number, height: number, color: RGBA, filled: bool): void
+	}
+	function get_file(filename: string): FilePtr
+	function get_deltatime(): number
+	function rgba(r: number, g: number, b: number, a: number): RGBA
+	function compare_rgba(color1: RGBA, color2: RGBA): boolean
 }