Runic is the primary alphabet of New Britannia.
Runic was also the primary alphabet in Richard Garriott's Ultima Series, and the Runic of Shroud of the Avatar is very similar to its predecessor with only a few letters altered (H, J, K, P, and W ) and letters representing sounds formed from two letters [TH, EE, NG, EA, and ST] being removed entirely.
While Runic was created by the development team, the actual font that is used by the fandom and even by the developers was designed by fan, Dame_Lori. This deed along with work on her own website have earned her the very first Order of New Britannia Empire award from Richard Garriott himself.
The runes in Shroud of the Avatar's Runic seems to be primarily based on Elder Futhark runes, the earliest form of runic alphabet used primarily from the 2nd to 8th centuries.
- Runic Language Comparison, http://forsakenvirtues.com/2013/07/05/new-pledge-tier-rewards-chart-runic-language-comparison/
Runic Font from ForsakenVirtues.com preserved on the Lycaeum.