diff --git a/demo1.cpp b/demo1.cpp
index aaa1d4f..555a494 100644
--- a/demo1.cpp
+++ b/demo1.cpp
@@ -10,8 +10,11 @@
   license: CC0 1.0
 */
 
-// redefine player's height
+// redefine some parameters
+#define GRAVITY_ACCELERATION (UNITS_PER_SQUARE * 3)
+#define PLAYER_JUMP_SPEED 700
 #define CAMERA_COLL_HEIGHT_BELOW ((3 * UNITS_PER_SQUARE) / 2)
+#define HORIZONTAL_FOV (UNITS_PER_SQUARE / 5)
 
 #include "general.hpp"
 
diff --git a/demo2.cpp b/demo2.cpp
index c9320a3..2b7e96f 100644
--- a/demo2.cpp
+++ b/demo2.cpp
@@ -22,7 +22,7 @@
 
 Player player;
 
-#define SHOT_SPEED 5 * UNITS_PER_SQUARE
+#define SHOT_SPEED 10 * UNITS_PER_SQUARE
 #define INFO_BAR_START 70
 #define TEXTURE_MAX_DISTANCE (UNITS_PER_SQUARE * 6)
 
@@ -900,10 +900,13 @@ int main()
 
       bool strafe = pokitto.aBtn();
 
-      if (pokitto.upBtn())
-        moveDirection = 1;
-      else if (pokitto.downBtn())
-        moveDirection = -1;
+      if (!strafe)
+      {
+        if (pokitto.upBtn())
+          moveDirection = 1;
+        else if (pokitto.downBtn())
+          moveDirection = -1;
+      }
 
       if (pokitto.rightBtn())
       {
diff --git a/demo3.cpp b/demo3.cpp
index 94b0609..95f9e9f 100644
--- a/demo3.cpp
+++ b/demo3.cpp
@@ -11,7 +11,9 @@
 */
 
 // redefine player's height
-#define PLAYER_SPEED (UNITS_PER_SQUARE * 7)
+#define PLAYER_SPEED (UNITS_PER_SQUARE * 6)
+#define HORIZONTAL_FOV ((3 * UNITS_PER_SQUARE) / 10)
+#define GRAVITY_ACCELERATION (UNITS_PER_SQUARE * 2)
 #define CAMERA_COLL_HEIGHT_BELOW ((3 * UNITS_PER_SQUARE) / 2)
 #define FPS 40
 #define HEAD_BOB_HEIGHT 150
diff --git a/general.hpp b/general.hpp
index f07a0d5..e36d928 100644
--- a/general.hpp
+++ b/general.hpp
@@ -26,7 +26,7 @@ Pokitto::Core pokitto;
 #endif
 
 #ifndef PLAYER_SPEED
-#define PLAYER_SPEED (2 * UNITS_PER_SQUARE)
+#define PLAYER_SPEED (4 * UNITS_PER_SQUARE)
 #endif
 
 #ifndef PLAYER_ROTATION_SPEED