This page of the guide to XCOM Chimera Squad has information on the Ironman difficulty and how to activate it. This extreme difficulty setting forces you to play on a single save, which carries a huge risk of failing the entire campaign.
The Ironman difficulty level modifier is well known from previous parts of the XCOM series. The Ironman mode is also available in XCOM Chimera Squad and you can enable it when you start a new campaign.
Here are the main rules of the Ironman mode in XCOM: Chimera Squad:
- Only one save slot available. You cannot have more than one save. This means you won't be able to go back in time and mend a mistake on the screen of City 31.
- A single sever will be created by the game automatically and will also be automatically updated. Manual saves are unavailable.
- If you fail a mission, you don't have to worry about losing the whole campaign. You can repeat the entire mission, that is all encounters that are part of it.
If you're looking for an even bigger challenge, you can also enable the Hardcore modifier. Its main rules are:
- Failing the mission equals losing the entire campaign. As a reminder: the mission may fail primarily if one of the team members dies, or if any of the mission objectives are not met (also in time).
- If the campaign is ever failed, the game deletes all saves from that campaign, so you can't go back and mend a mistake, a different decision, etc. This solution is like permadeath known from roguelike games.