The toolbar Launch Game button opens the Launch Game dialog. From here you pick a starting level, toggle launch options, then hit Start Alien: Isolation.

Options patch the game install and (for some UI mods) replace GFX files under DATA/UI.PAK. Some options aren't supported on all platforms — for example Cinematic Tools and Hot Reloading are Steam-only.

The Starting Level dropdown lists levels from the current game install. OpenCAGE prefers the level you're editing, otherwise your last used choice, otherwise the frontend.

• Choosing a normal level boots the game straight into that map — useful for testing a specific level without playing through from the start.
• Choosing FRONTEND launches into the normal title/front-end flow.

Your selection is remembered for next time.

These swap in OpenCAGE's modified pause/frontend/loading/game-over menus (by patching GFX files inside UI.PAK — see also the UI Editor):

• Enable Debug Checkpoints — adds debug checkpoints to the pause menu under Load Game. Checkpoints are per-map and load a scripted game state so you can jump to specific moments. They're created in level scripts with the DebugCheckpoint entity.
• Enable Level Selection — frontend menu with level selection (where you'd normally load a save)
• Enable Debug Loadscreen — loading screen that shows debug map info, and also loads quicker than normal by removing artificial wait times
• Add Quit To Menu On Death — game-over menu with quit-to-menu

Engine Patches

• Skip Frontend — skips the title screen when loading directly into a level
• Patch Current-Gen Optimisations — restores script functionality that was left out of the PC build (the game incorrectly still honours a “current gen” script flag). In vanilla this re-enables things like additional lighting, monitors, and effects.
• No UI — disables the in-game HUD. Also disables UI popups, which can make some actions impossible — useful for screenshots.
• Render Constant Ambient — full-bright “constant ambient” rendering mode

Debug Tools

• Enable UI Memory Overlay — shows current UI memory in an in-game overlay (cUI). Separate from Cathode DebugText entities.
• Enable Memory Logging — writes memory replay logs to a Mem_Replay_Logs folder

Steam-Only Tools

• Enable Hot Reloading — press INSERT in-game to hot reload the current level, handy for iterating on scripts without a full restart
• Enable Cinematic Tools — enables HattiWatti's Cinematic Tools. Antivirus software may block the injector; if so, add an exclusion for OpenCAGE's cinematic tools. The game can still launch without them.

Outside the Launch Game dialog:

• Options → Misc → Open Game On Save — after you save, OpenCAGE launches into the level you're editing. This bypasses the Launch Game dialog (so extras like Cinematic Tools / Hot Reloading from that dialog aren't applied). Off by default. See Options for the rest of the menu.