diff --git a/SpinnerGDD.md b/SpinnerGDD.md
index a347eaa..7d1c33d 100644
--- a/SpinnerGDD.md
+++ b/SpinnerGDD.md
@@ -84,3 +84,15 @@ The loop of levels will be to:
 2. Remind players of a previous enemy
 3. Combine them together to create a new challenge
 4. Repeat
+
+### **3.3 Game systems**
+
+- **Powerups**
+: `
+Portals - to achieve the appearance of non-Euclidean Changing gravity direction - used in some of the puzzles Trains - start/end of levels as well as being travel between levels (interacted by player) Ticket barriers - act as one way barriers in levels (interacted by player)
+`
+
+- **Enemies**
+
+- **Level flow**
+