Legacy Mode is way of playing the modern game but with a traditional look and feel, without the need to learn the new combat system. It’s an optional mode that you can switch on or off, so you can choose if and when you use it. Legacy Mode has a lot of other smaller tweaks to help give that traditional gameplay feel.

Legacy mode includes:

Traditional RuneScape combat, with no abilities.
Interfaces styled from the pre RS3 both resizable and fixed.
Old-style minimap icons.
Life points back to a max of 990.

Independent of Legacy Mode, we’re introducing some global changes to combat to make improvements for everyone, especially in PvP. These will also be available on Monday in the Combat Beta:

Reinstated '138' combat formula, tweaked to give melee, ranged and magic equal contribution.
Special attacks on weapons that had them before.
Critical hit chance will be replaced by strength bonuses which give higher max hits.
Finally, there are some overall balancing changes: more of your life points will come from stats rather than armour, and the penalties and bonuses across the combat triangle will be slightly relaxed, and damage from abilities has been tweaked to even out imbalances.