This mod is not suitable for core STEP
because it does add content. It would be a great choice for a STEP
package though. I have been using it extensively and I really enjoy it. There are some flaws, some balance issues that need to be addressed, but overall it is a much better balanced and much more challenging experience than is provided by vanilla skyrim. I have a level 50 stealth focused character and even at this level I have to be very careful with how I choose my engagements. There is a combination of leveled and deleveled scaling the author adds, so in some places bandits and most animals are just minor pests, but then a hargraven appears, or a bandit chief wakes up from a nap and you have a real fight on your hands.
The new skill tree, Wayfarer, seems to level up as you move about. It is of the class of none essential skills but it has some really nice perks that are worth investing in for some character classes. Pickpocket and Lockpicking have been merged into one skill, which comes at least a little closer to making that whole skill tree useful.
The weapons classes all split instead of being general. There are difference skill sets for shortswords, war axes, one handed maces, and also katana, scabers, shortsword, and nodochi weapons. The two handed weapon tree likewise has split perks, bows are split into long, short, and crossbow, and destruction magic is split by the element. The skill tree is designed so that you quickly get the flat damage boosts perks and then the specialization usually happens are higher levels, somewhere after 50 or 60 usually. The marksman skill tree is the exception; it splits very early and forces you to specialize with your ranged weapons rather quickly.
In the most recent updates the mod author has changed the base values on all of the in game armors in addition to the damage scaling. 10 armor rating provides a 1 percent damage reduction in physical attacks. There are a variety of skills and weapon classes that ignore armor rating to various degrees (crossbows almost entirely, other weapons by a smaller percentage). A heavily armored character can withstand many kinds of attacks very easily but be at a disadvantage against some others.
The unarmored route for mages has received very substantial buffs. Using the alteration school you can strengthen your defenses very easily. A novice level spell "oakflesh" improves player armor by 100 for 300 seconds, at the cost of a substantial amount of mana. The restoration school provides increasingly more powerful and cheaper ward spells for additional protection. Health and mana potions now act over time instead of instantly, and their total recovery amount has been buffed. Mages have some significant advantages against melee types, as most ice based spells slow movement speed, and projectile speed of most spells has been dramatically increased. I don't play a mage character myself, but I do find the mage enemies in the game to be among the most challenging. The restoration school now provides very powerful spells for undead enemies. The illusion spell system has been completely reworked. You now cast mirror images of your self, allowing you to teleport small distances, inflict damage or special kind of debuffs while different mirror images of you are active, and other very interesting effects. There seems to be more of a focus overall with both offensive alteration and illusion on chaining spells together. For example, alteration has a "push" and "pull" spell functions with different spell additions and perks that contribute to these new spell mechanics.
The mod also twists the speech craft tree so that your speechcraft effects the potency of dragon shouts. There are several perks for increasing damage, cool down duration, and the stealth skill tree can even make shouts silent. Merchants are much more cuthroat by default. I use a "Economics of Skyrim" on the "easy" setting with this mod, I have 2 points invested in the speech skill tree in the general buffs and I get an exchange rate of about 1/3rd or 1/5th the items value for selling, and pay around 2x or 3x the items value when buying. Its not a perfect system but overall I find that, even at level 50, I have to collect, craft, steal, and forage as much as I can to be able to afford the many things that I want.
The stealth tree has also been reworked. Bows now do 2x damage in stealth, and melee weapons 3x damage, with additional perks to increase the effectiveness of stealth attacks. There are options to instantly kill sleeping targets, and at high stealth levels you can kill humanoid targets instantly with daggers. When detected in steatlh enemies will search for you a lot longer. If you take out some guys buddy sitting right next to them, they no longer continue to obliviously sip their tea. Enemies site radius has been changed to binocular, so you can sneak by a little easier, but enemies in general detect better and more quickly. If you open a door, lower a draw bridge, or let loose an arrow near by they are likely to hear you. There are also perks that support playing mage assassins, with damage multipliers for spells, touch spells, and silent casting. The stealth skill is still abusable, but it takes forever. I have noticed a problem where enemies will stand right in front of you and take arrows to the face if you are in almost complete darkness. I uses RLWC and that happens for me rather often.
The mod also adds new mechanics to the game and fixes several bugs. If you are the right smithing perks you can break down weapons and armors into their base materials; for example iron shields and swords into iron. This helps a lot with making player crafting more viable in the much more difficult economy, and with hearthfire its nothing short of a godsend. Many smithing broken smithing recipes have been fixed. You can approach blacksmiths in towns and cities and request for them to craft armors and weapons for you via special order, and then can also improves you equipement for you, for a fee and based of a combination of their own skill and the item type being improved (ebony cost more than steel, ect). This makes it feasible to play a warrior type without smithing skills. New weapons and a select few armors have been added to the leveled list and smithing lists as well. In addition, all skill have been completely uncapped and many skill perks require greater than 100 skill points to use. Blocks now has a "timed block" feature, whereby if you hit block at special timings you can stagger as melee opponent.
has changed a lot as well. Enemies make use of specialized perks and timed blocks, in addition to new spells and spell effects. Enemies behave differently when in a group than in alone (they are more aggressive). Enemies will often use potions, run out of mana or arrows, and in general behave more like the player character. Mages and ranged weapon users will kite the player character and also, in general, aim really well.
Future updates may include a "lorecraft" approach to some or all of skill perks. The mod suffers some from having far more useful perks for a character class then is possible. I personally feel that the economy is not quite right. I would like to see an economics of skyrim merged with this mod, and then tweak the cost scaling some so buying is more viable and potion making is a lot less profitable. I feel like heavy armor skills provides challengeing enemies but extremely combersome and perhaps not very viable playing experience for the player character. I don't use the races plugin because some of the racial abilities I find immersion breaking; for instance dark elves will summon ancestor guardians when falling below 30% health that are nearly invincible and just kind of rape everything in sight. I feel like some of the static levels inhibit questing for anyone below level 30 or 40 and make the game in some respects a less fun, or the leveling mechanic more burdensome.
In my opinion though, it is the best balancing project for skyrim available by far. Using any other mod or a combination of mods, nothing I have tried is even close to SkyRe for interms of providing a challenging, interesting, and dynamic skyrim experience.