I suggest that @luxamman and @madsrh lead here.
We want to have this new theme feeling like ubuntu, which means, respecting the Ubuntu (and maybe ex Ubuntu Touch?) color palette and style. We don’t want to change add/remove extensions or change GNOME Shell behavior more than we did in 17.10.
I think the research should start from installing gnome-session
package on a fresh Ubuntu 17.10 (you need to never have changed your theme), logging into the GNOME session in GDM (which has the vanilla GNOME look and feel) as this is our starting point to check default Shell, icon and Adwaita (GTK) themes.
Of course, the rest of the team (and I will try to get some people from the design team coming by) is around for any questions!
For reference, the ubuntu design website (having color palette and other useful informations):
Ubuntu touch color palette:
http://colorpeek.com/#f7f7f7,cdcdcd,888888,666666,5d5d5d,3b3b3b,111111,e95420,762572,ed3146,3eb34f,19b6ee
In order of appearance:
Porcelain. Recommended for foregrounds.
Silk. Recommended for neutral action buttons and secondary text.
Ash. Recommended for subtitles and other tertiary content.
Graphite. Recommended for coloring dark themes’ background.
Slate. Recommended for text and action icons.
Inkstone. Recommended for foreground colors in dark themes.
Jet. Recommended for content coloring.
Orange. Recommended for branded elements, display progress and intensity, textual links on light backgrounds.
Purple. Recommended for proper nouns in list items.
Red. Recommended for negative and irreversible action buttons, errors and alerts.
Green. Recommended for positive action buttons.
Blue. Recommended for text selection and text cursor.
For more informations: Call for participation: an ubuntu default theme lead by the community? - Desktop - Ubuntu Community Hub
Feel free to post any source of inspiration and I let you leading from there!