i don't have any experience with the Train Wave, or the Main Train, or any other train mechanics added by The-Cave. please post a detailed description of what those are, how they work, and how to access and use them, including where to click and what research is required. it seems that information doesn't exist online yet.

Hi, thank you for asking. The most important point is that the startup system in The Cave has recently changed. The train-related game modes are no longer selected through Factorio’s normal Mod Settings menu.

HOW TO ACCESS THE NEW SETUP SYSTEM

1. Make sure you are using the latest version of The Cave.
2. From the Factorio main menu, start a completely New Game.
3. When the new game begins, The Cave’s custom Setup Lobby will open automatically.
4. Under the Game Mode section, select the type of game you want to play.
5. When you select Train Interiors or another special mode, a detailed information panel appears in the lobby. This panel explains what the mode does, how to use it, how to enter and leave the train, how liquid connections work, and the other included features.
6. You can then configure the Gameplay Modifiers, Features, and Technical Settings.
7. When everything is ready, press Confirm & Start to create the actual game world using your selected options.

You do not need to search through Mod Settings for these options anymore. The new Setup Lobby replaces the old selection method.

Please note that this setup screen is intended for a New Game. Loading an existing save will not normally reopen the new-game configuration lobby.

MAIN TRAIN AND TRAIN INTERIORS

The Main Train is the primary train used and tracked by the Train Interiors game mode. It is the train connected to the special interior system and the train-based gameplay mechanics. Other locomotives that you build do not automatically become the Main Train.

When Train Interiors is selected in the Setup Lobby, the relevant train system is prepared automatically when the game starts.

To enter the train interior:

1. Stand close to the Main Train’s locomotive.
2. Press Ctrl + Enter.
3. An on-screen prompt should appear when you are close enough.
4. Use Ctrl + Enter again to leave the interior.

You do not need to click a hidden button or complete research simply to enter or leave the Main Train.

The train interior contains the special train rooms and systems provided by the mode. This includes cargo and fluid-transfer functionality, interior expansion, power and battery systems, and additional features such as the Garden Floor and Garden Train. The Setup Lobby’s information panel explains these features when Train Interiors is selected.

TRAIN WAVE / TRAIN-BASED WAVE DEFENSE

If by “Train Wave” you mean the train-based Wave Defense system, it is not a separate train or item that you must craft. It is a challenge system centred around the Main Train.

When the relevant mode is selected:

• The Main Train becomes the main target of the wave system.
• The selected preparation or training period occurs before the attacks begin.
• After that period, enemy waves start automatically.
• The interface displays the current wave and information about the next wave.
• The system tracks the Main Train’s location and automatically handles the enemy attack routes and tunnels.
• You do not need to click a button to assign the train as the target.

The exact preparation time and other gameplay conditions depend on the options you select in the Setup Lobby.

RESEARCH REQUIREMENTS

No research is required to:

• Open the Setup Lobby.
• Select Train Interiors or the train-based challenge mode.
• Establish the Main Train.
• Enter or leave the train interior.
• Activate the core Wave Defense system selected at the start of the game.

Research is used later for upgrades and progression, such as expanding parts of the train interior, improving its power or battery systems, and unlocking further train-related upgrades. These technologies will appear normally in the technology tree after the game begins, and their costs are affected by the Research Difficulty selected in the Setup Lobby.

If you cannot see the Setup Lobby or the detailed game-mode descriptions, please first update The Cave and then test it by starting a completely New Game. The information is now provided directly inside the new startup interface instead of the standard Mod Settings screen.

Thank you for pointing out that this was not clear from the online information.