Okay, sorry Gatleos, should have tried to explain things in such a way that people who never played Megaman Battle Network would be able to understand.
So, an alternative way to explain the Custom stat is:
"The Custom stat decides the effectiveness of the "Cross Fusion" (a special mode that allows you to use the powers of another character)."
Also, yes, the game's supposed to be action-oriented, in a similar way to Diablo, Fallout, and many other games. There are no random encounters, as you can see the enemies. Enemies will react in different ways when seeing you.
As for that second question, I will try to describe it as briefly as possible:
- The game is set in the same universe as the MMBN series. Your char is a Navi (a kind of program used to navigate the internet). In the game you have a number of quests to complete, like in any RPG. Some of these are necessary, others are optional.
To defend yourself against viruses (the enemies) or evil Navis, you have an innate set of abilities, chips (that are re-usable attacks) and Cross Fusions (possibly other kinds of fusions will be added, but they are all similar).
Chips must be equipped. They work like cards in games like Magic or Pokemon: you play them to perform an action. Here they allow you to attack, defend yourself, make traps, change the environment, among other things. You can equip up to 25 chips, with up to 4 copies of the same chip. They can be used once per battle. When used outside of battle they have a cool down period.
Innate abilities are created and chosen when you create your Navi. They can be offensive, such as being able to shift your hand into a sword, defensive, such as making yourself become a statue, or misc., such as floating.
As with MMBN 4.5 players have no direct control over their character, they can only use the chips and suggest strategies.
When a enemy notices the player, or if he attacks an enemy, the battle starts. A circle shows the area of the fight. To escape you just need to step outside the arena. Other enemies may join in at any time. If you beat the enemy you get a reward based on how much damage you dealt, how much you took, and the length of the battle.
This, I think, is the gist of the gameplay.