A survival mode could be created without changing the main layout of the game but inserting as “replaying completed scenario”
Let me explain with an example. We have “Baia Ululante” and this scenario has been completed or at least, completed between the starting point (1) and the first check-point available (5).
Thus we set up, in this scenario, two entry points: on the beginning (1) and on the first check-point (5) as you can see into image displayed with « char on the left.
At the menu of the entry point, we put an option “survival mode” that inform us about how many level we need to complete in order to collect the revenue. In this case, they are 5.
We are going to pay double flags of the entry point. The (1) costs 3 flags, then 6 for the survival mode. If we manage to arrive at the end of 5 levels with the same heroes team, then we collect the sum of all the levels passed through otherwise we lost.
*** FIRST TWO SCENARIOS ***
Another suggestion. Currently, the game offer the option to retry (bring up in life the whole team, I think) in case we lost one level challenge. The price is 75 gems for any level which I have seen (up to 15, at the moment) which is a very expensive for the earliest scenario.
Again, the first two levels are kept by two dragons but they cost 3 flags for each level. Wouldn’t saner that the first scenario would cost 1 flag for each level and the second 2 flags for each level. Then 3 flags, and keep the current schema to increase the flags for others scenarios. But the first two could be used for practicing if they would be cheaper.
How to make them practicing levels? In survival mode. For 6 flags, it would be possible to cross 5 levels of the first scenario. The second for another 6 flags with 6 levels to cross. This make them cheaper for training.
*** UPPER SCENARIOS ***
Other scenario price for survival mode could be 2x or 3x of initial flag price depending the length. More lengthy, more difficult, more revenue. This should kept in consideration: paying less per level (e.g. 6÷8 flags for 3÷5 levels) but with an increased risk of loosing everything because the team should stay alive until the end to collect all the revenues taken across the levels.
*** LIMITATIONS ***
Except for the two first scenarios, other scenarios could NOT be engaged continuously.
Each scenario would have a timer which will prevent to be crossed again and again using survival mode.
This to avoid too easily too much resources. Obviously, these timers might be bypassed paying gems.
*** EXTENSION ***
Once the survival mode challenge is completed between the first two check-point an option could be offered to the player:
• take everything and end as scheduled
• pay some others flags to continue up to the end of the scenario but risking to loose everything in case of failure
• take half of what collected and quit
• continue but risk to loose everything
In this former case the number of flags would be greater than 2x. A reasonable factor would stay between 3x and 4x (in total a mean of half of the cost, if each level would be completed one-by-one: survival mode flags = N levels × K flags / 2).
Moreover, some check points could be not elevated as survival mode exit. In such a case the number of the levels to cross would be displayed at the beginning and that check-point will not have the « sign on it.
Survival mode could be implemented grouping levels among two check points in each scenario.