diff --git a/block.py b/block.py
new file mode 100644
index 0000000..d2ff0e5
--- /dev/null
+++ b/block.py
@@ -0,0 +1,38 @@
+import pygame as pg
+from sprite import Sprite
+
+class Block(Sprite):
+    COLOR = (0,0,255)
+    def __init__(self, rect_t):
+        super().__init__(rect_t[2:4])
+        self.map_rect = pg.Rect(rect_t)
+        self.image.fill(self.COLOR)
+
+    def update(self,map_rect):
+        self.rect.x =  self.map_rect.x - map_rect.x
+        self.rect.y =  self.map_rect.y - map_rect.y
+
+    def collide_ship(self, ship):
+          if self.map_rect.colliderect(ship.map_rect):
+                ship.velocity = 0
+                if ship.map_rect.centery <= self.map_rect.top:
+                    ship.map_pos.y -= ship.map_rect.bottom  - self.map_rect.top
+                elif ship.map_rect.centery >= self.map_rect.bottom:
+                    ship.map_pos.y +=  self.map_rect.bottom - ship.map_rect.top
+                if ship.map_rect.centerx <= self.map_rect.left:
+                    ship.map_pos.x -=  ship.map_rect.right - self.map_rect.left
+                elif ship.map_rect.centerx >= self.map_rect.right:
+                    ship.map_pos.x +=  self.map_rect.right - ship.map_rect.left
+
+
+if __name__=='__main__':
+    from ship import Ship
+
+    block = Block((0,0, 10, 20))
+    a_ship = Ship((10+Ship.SIZE/4, 20+Ship.SIZE/4), pg.Rect(0,0,100,100))
+    block.collide_ship(a_ship)
+    assert a_ship.map_pos.x == 10 + Ship.SIZE/2 and a_ship.map_pos.y == 20 + Ship.SIZE/2, "bad collision"
+    block = Block((0,0, 10, 40))
+    a_ship = Ship((10+Ship.SIZE/4, 20+Ship.SIZE/4), pg.Rect(0,0,100,100))
+    block.collide_ship(a_ship)
+    assert a_ship.map_pos.x == 10 + Ship.SIZE/2, "bad collision"
diff --git a/gem.py b/gem.py
new file mode 100644
index 0000000..cc7b0e9
--- /dev/null
+++ b/gem.py
@@ -0,0 +1,25 @@
+import pygame as pg
+from sprite import Sprite
+
+GREEN = (0,255,0)
+
+class Gem(Sprite):
+    RADIUS = 10
+    def __init__(self, pos):
+        size = (2*self.RADIUS,)*2
+        super().__init__(size)
+        rpos = (pos[0]- self.RADIUS, pos[1] - self.RADIUS)
+        self.map_rect = pg.Rect(rpos, size)
+        self.pos = pg.math.Vector2(pos)
+        pg.draw.circle(self.image, GREEN, (self.RADIUS,)*2, self.RADIUS)
+
+
+    def update(self, map_rect):
+        self.rect.x = self.pos.x - map_rect.x - self.RADIUS
+        self.rect.y = self.pos.y - map_rect.y - self.RADIUS
+
+    def collide_ship(self, ship):
+        rel_pos = self.pos - ship.map_rect.center
+        if rel_pos.length() < ship.SIZE/2 + self.RADIUS:
+            self.kill()
+
diff --git a/ship.py b/ship.py
new file mode 100644
index 0000000..8e2d5a3
--- /dev/null
+++ b/ship.py
@@ -0,0 +1,38 @@
+import pygame as pg
+from sprite import Sprite
+
+
+SHAPE = [(6,3), (1,5), (2,3), (1,1)]
+
+class Ship(Sprite):
+    SIZE = 40
+    COLOR =(255,0,0)
+    def __init__(self, pos, scr_rect):
+        super().__init__((self.SIZE,)*2)
+        self.map_pos = pg.math.Vector2(pos)
+        u = self.SIZE//6
+        self.shape = [pg.math.Vector2(p[0]*u,p[1]*u) for p in SHAPE]
+        self.rect.x = scr_rect.centerx - self.rect.width  / 2
+        self.rect.y = scr_rect.centery - self.rect.height / 2
+        self.velocity = 0
+        self.deceleration = 0
+        self.direction = pg.math.Vector2((1,0))
+        self.change = pg.math.Vector2((0,0))
+
+    def update(self, rot_vector):
+       center = self.SIZE/2
+       def rotate(p):
+           x0 = p[0]-center
+           y0 = p[1]-center
+           x1 = x0 * rot_vector.x - y0 * rot_vector.y
+           y1 = x0 * rot_vector.y + y0 * rot_vector.x
+           return (x1 + center, y1 + center)
+       new_shape = list(map(rotate, self.shape))
+       self.image.fill(self.image.get_colorkey())
+       pg.draw.polygon(self.image, self.COLOR, new_shape)
+
+    @property
+    def map_rect(self):
+        return pg.Rect(
+                (self.map_pos.x-self.SIZE/2+1, self.map_pos.y-self.SIZE/2+1),
+                (self.SIZE-2, self.SIZE-2))
diff --git a/sprite.py b/sprite.py
new file mode 100644
index 0000000..d36dd9c
--- /dev/null
+++ b/sprite.py
@@ -0,0 +1,15 @@
+
+import pygame as pg
+
+PINK = (255,0,255)
+
+class Sprite(pg.sprite.Sprite):
+
+    def __init__(self, size):
+        super().__init__()
+        self.image = pg.Surface(size)
+        self.image.fill(PINK)
+        self.image.set_colorkey(PINK)
+        self.rect = self.image.get_rect()
+        
+