diff --git a/src/gamescenebase.cpp b/src/gamescenebase.cpp
index 70be162..856fef5 100644
--- a/src/gamescenebase.cpp
+++ b/src/gamescenebase.cpp
@@ -41,6 +41,7 @@ namespace curry {
 	} //unnamed namespace
 
 	GameSceneBase::GameSceneBase (cloonel::SDLMain* parSdlMain) :
+		m_time0(std::chrono::steady_clock::now()),
 		m_input(std::make_unique<cloonel::InputBag>()),
 		m_sdlmain(parSdlMain),
 		m_wants_to_quit(false)
@@ -53,6 +54,8 @@ namespace curry {
 	void GameSceneBase::prepare() {
 		m_wants_to_quit = false;
 		this->on_prepare();
+
+		m_time0 = std::chrono::steady_clock::now();
 	}
 
 	void GameSceneBase::destroy() noexcept {
@@ -69,12 +72,16 @@ namespace curry {
 	}
 
 	void GameSceneBase::exec() {
+		const auto time1 = std::chrono::steady_clock::now();
+
 		const bool quit = DoEvents(*m_input, m_sdlmain);
 		m_input->KeyStateUpdateFinished();
 		if (quit)
 			set_wants_to_quit();
 
-		this->on_update();
+		const float delta = std::chrono::duration<float>(time1 - m_time0).count();
+		m_time0 = time1;
+		this->on_update(delta);
 	}
 
 	cloonel::SDLMain* GameSceneBase::sdl_main() {
diff --git a/src/gamescenebase.hpp b/src/gamescenebase.hpp
index 41737a9..f523e2e 100644
--- a/src/gamescenebase.hpp
+++ b/src/gamescenebase.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <memory>
+#include <chrono>
 
 namespace cloonel {
 	class InputBag;
@@ -24,11 +25,12 @@ namespace curry {
 	protected:
 		virtual void on_prepare() = 0;
 		virtual void on_destroy() noexcept = 0;
-		virtual void on_update() = 0;
+		virtual void on_update (float parDeltaT) = 0;
 		cloonel::SDLMain* sdl_main();
 		cloonel::InputBag& input_bag();
 
 	private:
+		std::chrono::time_point<std::chrono::steady_clock> m_time0;
 		std::unique_ptr<cloonel::InputBag> m_input;
 		cloonel::SDLMain* m_sdlmain;
 		bool m_wants_to_quit;
diff --git a/src/ingamescene.cpp b/src/ingamescene.cpp
index 271dd47..1c746cd 100644
--- a/src/ingamescene.cpp
+++ b/src/ingamescene.cpp
@@ -4,6 +4,7 @@
 #include "key.hpp"
 #include "inputbag.hpp"
 #include <SDL2/SDL.h>
+#include <algorithm>
 
 namespace curry {
 	namespace {
@@ -47,15 +48,21 @@ namespace curry {
 		m_worldtiles.load(RESOURCES_PATH "textures.png", *this->sdl_main());
 	}
 
-	void IngameScene::on_update() {
+	void IngameScene::on_update (float parDeltaT) {
+		const float speed_per_sec =
+			static_cast<float>(
+				std::max(m_world.tile_size().x(), m_world.tile_size().y())
+			) * 1.5f;
+
+		const float speed = parDeltaT * speed_per_sec;
 		if (cloonel::IsPressed(input_bag(), ActionRight))
-			m_viewport.set_position(m_viewport.position() + vec2i(1, 0));
+			m_viewport.set_position(m_viewport.position() + vec2f(speed, 0));
 		if (cloonel::IsPressed(input_bag(), ActionLeft))
-			m_viewport.set_position(m_viewport.position() - vec2i(1, 0));
+			m_viewport.set_position(m_viewport.position() - vec2f(speed, 0));
 		if (cloonel::IsPressed(input_bag(), ActionUp))
-			m_viewport.set_position(m_viewport.position() - vec2i(0, 1));
+			m_viewport.set_position(m_viewport.position() - vec2f(0, speed));
 		if (cloonel::IsPressed(input_bag(), ActionDown))
-			m_viewport.set_position(m_viewport.position() + vec2i(0, 1));
+			m_viewport.set_position(m_viewport.position() + vec2f(0, speed));
 
 		const auto tilesize(m_world.tile_size());
 		for (auto tile : m_viewport) {
diff --git a/src/ingamescene.hpp b/src/ingamescene.hpp
index 1244409..c41cef4 100644
--- a/src/ingamescene.hpp
+++ b/src/ingamescene.hpp
@@ -18,7 +18,7 @@ namespace curry {
 	protected:
 		virtual void on_prepare() override;
 		virtual void on_destroy() noexcept override;
-		virtual void on_update() override;
+		virtual void on_update (float parDeltaT) override;
 
 	private:
 		WorldGrid m_world;
diff --git a/src/tileiterator.cpp b/src/tileiterator.cpp
index 0f108b9..ca9e73d 100644
--- a/src/tileiterator.cpp
+++ b/src/tileiterator.cpp
@@ -25,7 +25,10 @@ namespace curry {
 		m_index(parEnd ? -1 : 0)
 	{
 		assert(m_viewport);
-		m_pixel_pos = first_col_starting_pixel(m_viewport->position(), m_viewport->world()->tile_size());
+		m_pixel_pos = first_col_starting_pixel(
+			static_cast<vec2i>(m_viewport->position()),
+			m_viewport->world()->tile_size()
+		);
 	}
 
 	void TileIterator::increment() {
@@ -34,7 +37,7 @@ namespace curry {
 		const WorldGrid& world = *m_viewport->world();
 		vec2i tile_size(world.tile_size());
 		auto first_tile_pos = first_col_starting_pixel(
-			m_viewport->position(),
+			static_cast<vec2i>(m_viewport->position()),
 			m_viewport->world()->tile_size()
 		);
 		vec2i pos(tile_size * m_index + first_tile_pos);
diff --git a/src/worldviewport.cpp b/src/worldviewport.cpp
index 9044606..3e286a8 100644
--- a/src/worldviewport.cpp
+++ b/src/worldviewport.cpp
@@ -15,11 +15,11 @@ namespace curry {
 		return m_world;
 	}
 
-	const vec2i& WorldViewport::position() const {
+	const vec2f& WorldViewport::position() const {
 		return m_position;
 	}
 
-	const vec2i& WorldViewport::size() const {
+	const vec2f& WorldViewport::size() const {
 		return m_size;
 	}
 
@@ -31,7 +31,7 @@ namespace curry {
 		return iterator(this, true);
 	}
 
-	void WorldViewport::set_position (const vec2i& parPos) {
+	void WorldViewport::set_position (const vec2f& parPos) {
 		m_position = parPos; //TODO: assert validity
 	}
 } //namespace curry
diff --git a/src/worldviewport.hpp b/src/worldviewport.hpp
index 5daf6b6..eb0bee8 100644
--- a/src/worldviewport.hpp
+++ b/src/worldviewport.hpp
@@ -12,17 +12,17 @@ namespace curry {
 
 		WorldViewport (WorldGrid* parWorld, vec2i parSize);
 		const WorldGrid* world() const;
-		const vec2i& position() const;
-		const vec2i& size() const;
+		const vec2f& position() const;
+		const vec2f& size() const;
 
-		void set_position (const vec2i& parPos);
+		void set_position (const vec2f& parPos);
 
 		iterator begin();
 		iterator end();
 
 	private:
-		vec2i m_position;
-		vec2i m_size;
+		vec2f m_position;
+		vec2f m_size;
 		WorldGrid* m_world;
 	};
 } //namespace curry