diff --git a/2019/day11/day11.py b/2019/day11/day11.py
index 77257cb..c308a3b 100644
--- a/2019/day11/day11.py
+++ b/2019/day11/day11.py
@@ -60,6 +60,6 @@ if __name__ == "__main__":
     import fileinput
     with fileinput.input() as f:
         main(f, part=1)
-    with fileinput.input() as f:
+    #with fileinput.input() as f:
         #main(f, part=2)  # FIXME unable to run both parts simultaneously
 
diff --git a/2019/day13/day13.py b/2019/day13/day13.py
new file mode 100644
index 0000000..06ce72c
--- /dev/null
+++ b/2019/day13/day13.py
@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+# TODO replace PYTHONPATH hack with a proper solution, like making intcode an
+# installed module https://stackoverflow.com/a/50194143
+import sys
+import time
+from itertools import zip_longest
+from pathlib import Path
+from collections import defaultdict, Counter
+from dataclasses import dataclass
+
+sys.path.append(str(Path(__file__).absolute().parent.parent / "intcode"))
+from intcode import interpret_intcode, Interpreter
+
+@dataclass
+class State:
+    grid: ...
+    score = 0
+    bounds = None
+    paddle_pos = None
+    ball_pos = None
+    stopped = False
+
+
+def grouper(n, iterable):
+    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
+    args = [iter(iterable)] * n
+    return zip_longest(*args)
+
+
+def part1(program):
+    interpreter = interpret_intcode(program)
+    game = { (x, y): tile for x, y, tile in grouper(3, interpreter.stdout) }
+    print("Part 1: ", len([x for x in game.values() if x == 2]))
+
+
+def parse_map(output):
+    grid = {}
+    score = None
+    for x, y, tile in grouper(3, output):
+        if (x, y) == (-1, 0):
+            score = tile
+        else:
+            grid[x,y] = tile
+    paddle = next((k for k, v in grid.items() if v == 3), None)
+    ball = next((k for k, v in grid.items() if v == 4), None)
+    bounds = (max(x for x, y in grid.keys()),
+              max(y for x, y in grid.keys()))
+    return grid, bounds, score, paddle, ball
+
+
+def update_state(state: State, stdout):
+    grid, bounds, score, paddle, ball = parse_map(stdout)
+    if ball is None:
+        state.stopped = True
+    if state.bounds is None:  # only set bounds the first time
+        state.bounds = bounds
+    if score is not None:
+        state.score = score
+    if paddle is not None:
+        state.paddle_pos = paddle
+    if ball is not None:
+        state.ball_pos = ball
+    if grid is None:
+        state.grid = grid
+    else:
+        # merge grid
+        for (x, y), v in grid.items():
+            state.grid[x,y] = v
+    return state
+
+
+def part2(program):
+    program[0] = 2
+    interpreter = Interpreter(program)
+    state = State({})
+    while not interpreter.halted:
+        interpreter.interpret(break_on_output=False, break_on_input=True)
+        state = update_state(state, interpreter.stdout)
+        if state.stopped:
+            break
+        #print_map(state)
+        interpreter.stdout.clear()
+        paddle_x, ball_x = state.paddle_pos[0], state.ball_pos[0]
+        if paddle_x < ball_x:  # move right
+            interpreter.stdin.append(1)
+        elif paddle_x > ball_x:  # move left
+            interpreter.stdin.append(-1)
+        else:
+            interpreter.stdin.append(0)
+    print("Part 2: ", state.score)
+
+
+def print_map(state):
+    clear = "\033[2J"
+    tiles = { 0: " ", 1: "#", 2: "~", 3: "_", 4: "O" }
+    max_x, max_y = state.bounds
+    print(clear)
+    for y in range(max_y + 1):
+        l = []
+        for x in range(max_x + 1):
+            tile = state.grid[x,y]
+            l.append(tiles[tile])
+        print("".join(l))
+    time.sleep(1/60)
+
+
+def main(inp):
+    program = [int(x) for x in inp.readline().rstrip().split(",")]
+    part1(program)
+    part2(program)
+
+if __name__ == "__main__":
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as raw_input:
+        main(raw_input)
+
diff --git a/2019/intcode/intcode.py b/2019/intcode/intcode.py
index 52ceb63..edaf987 100644
--- a/2019/intcode/intcode.py
+++ b/2019/intcode/intcode.py
@@ -165,25 +165,26 @@ class Interpreter:
     def __repr__(self):
         return f"Interpreter(ip={self.ip}, stdin={self.stdin}, stdout={self.stdout}, halted={self.halted})"
 
-    def next_instruction(self):
-        instruction = Instruction(self.memory, self.ip, self.base)
-        if instruction.operation == Operation.INPUT:
-            instruction.input = self.stdin.pop(0)
-        self.ip = instruction.handle()
-        self.base = instruction.base
-        logging.debug(f"IP {self.ip}")
-        if instruction.output is not None:
-            self.stdout.append(instruction.output)
-        elif instruction.halted:
-            self.halted = True
-        return instruction
-
-    def interpret(self, break_on_output=True):
-        while instruction := self.next_instruction():
-            if self.halted:
-                break
-            if break_on_output and instruction.output is not None:
-                break
+    def interpret(self, break_on_input=False, break_on_output=True):
+        while not self.halted:
+            # fetch next instruction
+            instruction = Instruction(self.memory, self.ip, self.base)
+            # pause if INP + break on input
+            if instruction.operation == Operation.INPUT:
+                if break_on_input and self.stdin == []:
+                    break
+                else:
+                    instruction.input = self.stdin.pop(0)
+            # execute instruction
+            self.ip = instruction.handle()
+            self.base = instruction.base
+            logging.debug(f"IP {self.ip}")
+            if instruction.output is not None:
+                self.stdout.append(instruction.output)
+                if break_on_output:
+                    break
+            if instruction.halted:
+                self.halted = True
 
 
 def interpret_intcode(program, stdin=[]):