Depending on your difficulty level, you will trigger a salvation mission that gives you a $tarch reward when you have less than 200 $tarch in your bank. But prevention is better than cure! Here are some tips:
1) Ensure that you send your best spies on missions. Highly successful missions earn you higher ranks and more $tarch!
2) Equip gadgets that give bonuses on mission rewards. Cat Paws, anyone?
3) Activate spot bonuses that give $tarch boosts. Try Broccoli Tree, Phone Booth, and Pile of Homework.
4) Accept requests in the mailbox and do side missions! Be wary not to fail them since it will penalize your $tarch instead.
5) Be mindful of your spending. Training can be expensive, use it sparingly on the right spies!
6) Wait for Kumo to bring back some $tarch.
7) If in dire straits, sell your gadgets, if any.
It all boils down to one thing - your spies need more training. Keep training your spies as you progress through the game. Higher level missions require much, much stronger spies!
Choose your actions wisely during mission planning - if you use actions that the obstacles are resistant/immune against, the mission will be riskier! You can try researching alternative routes by unlocking grids (Level 2 missions onward). You can also equip gadgets and activate combos to boost your stats.
Enemy resistances and weaknesses are generated randomly during special missions. You have to make a guess on their weakness and react fast. Some things you can do:
1) Select the right supporting spies to ensure that Ren is strong in all 4 stats so that you can react accordingly. Do not start the mission when it says HIGH RISK!
2) Equip gadgets and activate combos to boost the stats even further.
3) Have a skill ready to boost each one of the four stats, you never know when you'll need them!
4) Save your skills for more difficult opponents, like Bosses and Guard Captains.
Most of them are unlocked by decrypting codices. You can get codices by completing missions. Missions that accomplish a rank of A / S have a better chance to give higher level codices, so make sure you send your best spies!
You can also unlock certain decorations by completing side mission requests.
Normal mode is the way the game was meant to be played. If you are new to simulation games, I would suggest to try Easy mode first - the multitasking can get quite hectic! Try out the Hard mode if you'd like some challenge in your life. You've been warned.
The difficulty levels mainly differ by the amount of $tarch reward and the mission expiry duration.
You will face a series of opponents and you can choose your actions against them on the spot by clicking on the corresponding stats (round buttons) or skills (rectangular buttons). You can change your actions during the battle by clicking different buttons. However, skills only last a certain number of turns, so be sure to use them at the right time!