For those who wonder or/and want to try stealthy raids, I can give you a quick tip: be quick!
Why? Because in this game there is a feature called Visibility. If I remember well, you have a total of 3000 Visibility (correct me if I'm wrong). Once you started your stealthy attack, you will see a bar filling up, increasing quite quickly (from 0 to 3000). This is the Visibility bar. If it reaches the maximum, you are detected and cannot do anymore stealthy attack.
But you may remember in your library, if you've unlocked the Stealthy hacks (the branch containing Leech, Access, etc.) you may see that they have Visibility points. Well, not only your Visibility increases all by itself when you start to be sneaky, it also increases when you put down some of these hacks.
Let's say you have put 5 Accesses and 3 Leeches (which only work ON mines, storages and Core ; nowhere else) at the first level, you will get 150*5 and 26*3 = 828 Visibility. So if you don't put down anything else, you would have 2172 Visibility left. That's enough for a few more stealthy hacks
but that's not that easy. Well the thing is that you will more likely be closer to 1900 left because for all these hacks to be pulled up, you had to wait 8 seconds (1 per Access and 1 per Leech), and the time flies away pretty quickly...
Stealthy attacks are hard to use to get a victory, but it's a fun way to attack. One last tip : if it happens you use any hack that isn't stealthy, the sneaky attack will immediately end. Finally, if you run out of Visibility, even if you had some Leeches downloading ressources or destroying the Core, they will disappear.
To the developpers, I hope the Visibility will increase when you level your Core to a higher level, as it will get tougher to do sneaky attack.