diff --git a/client/src/components/LeftPanel.tsx b/client/src/components/LeftPanel.tsx
index 0e75963..ecc3754 100644
--- a/client/src/components/LeftPanel.tsx
+++ b/client/src/components/LeftPanel.tsx
@@ -5,23 +5,30 @@ import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
 import { faLock, faLockOpen, faBook, faHammer, faBan } from '@fortawesome/free-solid-svg-icons'
 import Markdown from './Markdown';
 
-
-function LeftPanel({ tactics, inventory, showSidePanel, setShowSidePanel }) {
+function LeftPanel({ tactics, lemmas } :
+  {lemmas: {name: string, locked: boolean, disabled: boolean}[],
+   tactics: {name: string, locked: boolean, disabled: boolean}[]}) {
 
   return (
     <>
-    <div className="tactic-inventory">
-      {  tactics.map (({name, locked, disabled}) => {
-        const icon = locked ? <FontAwesomeIcon icon={faLock} /> :
-                     disabled ? <FontAwesomeIcon icon={faBan} /> : ""
-        const className = locked ? "locked" : disabled ? "disabled" : ""
-        return <div className={`tactic ${className}`}>{icon} {name}</div>
-    })}
+    <div className="inventory">
+      { tactics.map(tac => <InventoryItem name={tac.name} locked={tac.locked} disabled={tac.disabled} />) }
     {/* TODO: Click on Tactic: show info
       TODO: click on paste icon -> paste into command line */}
     </div>
+
+    <div className="inventory">
+      { lemmas.map(lem => <InventoryItem name={lem.name} locked={lem.locked} disabled={lem.disabled} />) }
+    </div>
     </>
   )
 }
 
+function InventoryItem({name, locked, disabled}) {
+  const icon = locked ? <FontAwesomeIcon icon={faLock} /> :
+               disabled ? <FontAwesomeIcon icon={faBan} /> : ""
+  const className = locked ? "locked" : disabled ? "disabled" : ""
+  return <div className={`item ${className}`}>{icon} {name}</div>
+}
+
 export default LeftPanel;
diff --git a/client/src/components/Level.tsx b/client/src/components/Level.tsx
index 77134bc..4b1e597 100644
--- a/client/src/components/Level.tsx
+++ b/client/src/components/Level.tsx
@@ -67,13 +67,8 @@ function Level() {
 
   const [commandLineMode, setCommandLineMode] = useState(true)
   const [commandLineInput, setCommandLineInput] = useState("")
-  const [showSidePanel, setShowSidePanel] = useState(true)
   const [canUndo, setCanUndo] = useState(initialCode.trim() !== "")
 
-  const toggleSidePanel = () => {
-    setShowSidePanel(!showSidePanel)
-  }
-
   const theme = useTheme();
 
   useEffect(() => {
@@ -184,8 +179,7 @@ function Level() {
         </EditorContext.Provider>
       </div>
       <div className="doc-panel">
-        {!level.isLoading && <LeftPanel tactics={level?.data?.tactics} inventory={level?.data?.lemmas}
-          showSidePanel={showSidePanel} setShowSidePanel={setShowSidePanel} />}
+        {!level.isLoading && <LeftPanel tactics={level?.data?.tactics} lemmas={level?.data?.lemmas} />}
       </div>
     </Split>
   </>
diff --git a/client/src/components/inventory.css b/client/src/components/inventory.css
index 40f98c1..0cd3c44 100644
--- a/client/src/components/inventory.css
+++ b/client/src/components/inventory.css
@@ -1,16 +1,16 @@
-.tactic-inventory {
+.inventory {
   display: flex;
   gap: .5em;
   flex-wrap : wrap;
   padding: 1em
 }
 
-.tactic-inventory .tactic {
+.inventory .item {
   border: solid 1px #aaa;
   padding: .1em .5em;
 }
 
-.tactic-inventory .tactic.locked,
-.tactic-inventory .tactic.disabled {
+.inventory .item.locked,
+.inventory .item.disabled {
   color: #aaa;
 }
diff --git a/client/src/state/api.ts b/client/src/state/api.ts
index 23e3de1..5fb947c 100644
--- a/client/src/state/api.ts
+++ b/client/src/state/api.ts
@@ -15,7 +15,7 @@ interface LevelInfo {
   introduction: null|string,
   index: number,
   tactics: {name: string, disabled: boolean, locked: boolean}[],
-  lemmas: any[],
+  lemmas: {name: string, disabled: boolean, locked: boolean}[],
   descrText: null|string,
   descrFormat: null|string,
 }
diff --git a/server/leanserver/GameServer/Commands.lean b/server/leanserver/GameServer/Commands.lean
index d0174dc..6e3085e 100644
--- a/server/leanserver/GameServer/Commands.lean
+++ b/server/leanserver/GameServer/Commands.lean
@@ -264,32 +264,50 @@ elab "MakeGame" : command => do
   if game.worlds.hasLoops then
     throwError "World graph has loops!"
 
-  -- Compute which tactics are available in which level:
+  -- Compute which tactics/lemmas are available in which level:
   let mut newTacticsInWorld : HashMap Name (HashSet Name) := {}
   let mut allTactics : HashSet Name := {}
+  let mut newLemmasInWorld : HashMap Name (HashSet Name) := {}
+  let mut allLemmas : HashSet Name := {}
   for (worldId, world) in game.worlds.nodes.toArray do
     let mut newTactics : HashSet Name:= {}
+    let mut newLemmas : HashSet Name:= {}
     for (_, level) in world.levels.toArray do
       newTactics := newTactics.insertMany level.newTactics
       allTactics := allTactics.insertMany level.newTactics
+      newLemmas := newLemmas.insertMany level.newLemmas
+      allLemmas := allLemmas.insertMany level.newLemmas
     newTacticsInWorld := newTacticsInWorld.insert worldId newTactics
+    newLemmasInWorld := newLemmasInWorld.insert worldId newLemmas
 
-  let tacticAvailability₀ : HashMap Name TacticAvailability :=
+  -- Basic tactic/lemma availability: all locked, none disabled.
+  let Availability₀ : HashMap Name Availability :=
     HashMap.ofList $
       allTactics.toList.map fun name =>
         (name, {name, locked := true, disabled := false})
+  let lemmaAvailability₀ : HashMap Name Availability :=
+    HashMap.ofList $
+      allLemmas.toList.map fun name =>
+        (name, {name, locked := true, disabled := false})
 
-  let mut tacticsInWorld : HashMap Name (HashMap Name TacticAvailability) := {}
+  -- Availability after a given world
+  let mut tacticsInWorld : HashMap Name (HashMap Name Availability) := {}
+  let mut lemmasInWorld : HashMap Name (HashMap Name Availability) := {}
   for (worldId, _) in game.worlds.nodes.toArray do
-    let mut tactics : HashMap Name TacticAvailability := tacticAvailability₀
+    let mut tactics := Availability₀
+    let mut lemmas := lemmaAvailability₀
     let predecessors := game.worlds.predecessors worldId
     for predWorldId in predecessors do
       for tac in newTacticsInWorld.find! predWorldId do
         tactics := tactics.insert tac {name := tac, locked := false, disabled := false}
+      for lem in newLemmasInWorld.find! predWorldId do
+        lemmas := lemmas.insert lem {name := lem, locked := false, disabled := false}
     tacticsInWorld := tacticsInWorld.insert worldId tactics
+    lemmasInWorld := lemmasInWorld.insert worldId lemmas
 
   for (worldId, world) in game.worlds.nodes.toArray do
     let mut tactics := tacticsInWorld.find! worldId
+    let mut lemmas := lemmasInWorld.find! worldId
 
     let levels := world.levels.toArray.insertionSort fun a b => a.1 < b.1
 
@@ -298,9 +316,20 @@ elab "MakeGame" : command => do
         tactics := tactics.insert tac {name := tac, locked := false, disabled := false}
       for tac in level.disabledTactics do
         tactics := tactics.insert tac {name := tac, locked := false, disabled := true}
+      for lem in level.newLemmas do
+        lemmas := lemmas.insert lem {name := lem, locked := false, disabled := false}
+      for lem in level.disabledLemmas do
+        lemmas := lemmas.insert lem {name := lem, locked := false, disabled := true}
 
       let tacticArray := tactics.toArray
         |>.insertionSort (fun a b => a.1.toString < b.1.toString)
         |>.map (·.2)
+
+      let lemmaArray := lemmas.toArray
+        |>.insertionSort (fun a b => a.1.toString < b.1.toString)
+        |>.map (·.2)
+
       modifyLevel ⟨← getCurGameId, worldId, levelId⟩ fun level => do
-        return {level with tactics := tacticArray}
+        return {level with
+          tactics := tacticArray
+          lemmas := lemmaArray}
diff --git a/server/leanserver/GameServer/EnvExtensions.lean b/server/leanserver/GameServer/EnvExtensions.lean
index 9b5aa67..1dc476c 100644
--- a/server/leanserver/GameServer/EnvExtensions.lean
+++ b/server/leanserver/GameServer/EnvExtensions.lean
@@ -144,7 +144,7 @@ structure LevelId where
   level : Nat
 deriving Inhabited
 
-structure TacticAvailability where
+structure Availability where
   name : Name
   locked : Bool
   disabled : Bool
@@ -176,7 +176,7 @@ structure GameLevel where
   -- only these tactics are allowed in this level (ignore if empty):
   onlyTactics: Array Name := default
   -- tactics in this level (computed by `MakeGame`):
-  tactics: Array TacticAvailability := default
+  tactics: Array Availability := default
   -- new lemmas introduces by this level:
   newLemmas: Array Name := default
   -- lemmas exceptionally forbidden in this level:
@@ -184,7 +184,7 @@ structure GameLevel where
   -- only these lemmas are allowed in this level (ignore if empty):
   onlyLemmas: Array Name := default
   -- lemmas in this level (computed by `MakeGame`):
-  lemmas: Array LemmaDocEntry := default
+  lemmas: Array Availability := default
   hints: Array GoalHintEntry := default
   goal : TSyntax `Lean.Parser.Command.declSig := default
   descrText: String := default
diff --git a/server/leanserver/GameServer/Game.lean b/server/leanserver/GameServer/Game.lean
index 9959d48..4cedcda 100644
--- a/server/leanserver/GameServer/Game.lean
+++ b/server/leanserver/GameServer/Game.lean
@@ -41,8 +41,8 @@ Fields:
 structure LevelInfo where
   index : Nat
   title : String
-  tactics: Array TacticAvailability
-  lemmas: Array LemmaDocEntry
+  tactics: Array Availability
+  lemmas: Array Availability
   introduction : String
   descrText : String := ""
   descrFormat : String := ""