diff --git a/doc/protocol.txt b/doc/protocol.txt
new file mode 100644
index 0000000..b7b433c
--- /dev/null
+++ b/doc/protocol.txt
@@ -0,0 +1,32 @@
+Minetest-c55 protocol (incomplete, early draft):
+Updated 2011-06-18
+
+A custom protocol over UDP.
+
+Initialization:
+- A dummy reliable packet with peer_id=PEER_ID_INEXISTENT=0 is sent to the server:
+	- Actually this can be sent without the reliable packet header, too, i guess,
+	  but the sequence number in the header allows the sender to re-send the
+	  packet without accidentally getting a double initialization.
+	- Packet content:
+		# Basic header
+		u32 protocol_id = PROTOCOL_ID = 0x4f457403
+		u16 sender_peer_id = PEER_ID_INEXISTENT = 0
+		u8 channel = 0
+		# Reliable packet header
+		u8 type = TYPE_RELIABLE = 3
+		u16 seqnum = SEQNUM_INITIAL = 6550
+		# Original packet header
+		u8 type = TYPE_ORIGINAL = 1
+		# And no actual payload.
+- Server responds with something like this:
+	- Packet content:
+		# Basic header
+		u32 protocol_id = PROTOCOL_ID = 0x4f457403
+		u16 sender_peer_id = PEER_ID_INEXISTENT = 0
+		u8 channel = 0
+		# Control packet header
+		u8 type = TYPE_CONTROL = 0
+		u8 controltype = CONTROLTYPE_SET_PEER_ID = 1
+		u16 peer_id_new = assigned peer id to client (other than 0 or 1)
+
diff --git a/src/main.cpp b/src/main.cpp
index 10ece4c..ae52bc3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -346,6 +346,9 @@ TODO: Add a per-sector database to store surface stuff as simple flags/values
 	  - Surface ground type
 	  - Trees?
 
+TODO: Restart irrlicht completely when coming back to main menu from game.
+	- This gets rid of everything that is stored in irrlicht's caches.
+
 Making it more portable:
 ------------------------