Moss features:
Moss's core feature is the the ability for a group to pick the fit-for-purpose tooling that's appropriate for that group. This makes it it very easy for groups to evolve their digital tooling their purpose and needs evolve.
Furthermore, assets generated in one Tool can be linked to and embedded in Assets created by other tools. This creates an "asset-centric" computing environment rather than the usual application centric model. this means, for example, that if a given tool doesn't have "commenting" you can just link in a comment thread from your chat tool.
Here are a number of Tools that have already been developed that you can use in your groups:
Vines: Provides the usual chat functionality: topics, channels, attachments, mentions, etc.
Slate: Provides real-time collaborative drawing. Fully featured diagrams and drawing tools based on the Excalidraw open-source library. 
Notebooks: Provides real-time collaborative editing of MarkDown documents. Includes syntax-highlighting, version history, and more. 
KanDo: Provides robust KanBan functionality with commenting, assignments, labels, categories, checklists and more. 
TalkingStickies: Provides real-time stickies-boards for ideation, meeting agendas, retros, etc... 
Presence: Provides video conferencing with screen sharing, and creation of public and private rooms. 
Emergence: Provides full-featured open-space conference management. Create site-maps, spaces, sessions, scheduling, real-time activity-feed and sense-making with tag-clouds and note-taking. 
Converge: Allows stakeholders to shift focus from outcomes to refining a set of criteria that has maximal support. Using this list, they can evaluate and refine proposals to meet those broadly supported criteria.
Who's In?: Provides a frame for group members to propose collective actions or events which other then agree to participate in as long as all necessary roles are filled. Thus collective actions grow viably from idea to reality. 
SnapMail: Provides email-like in-group messaging with attachments, replies, etc. 
Where: Provides a generalized grammar for creating shared maps for groups to see the emergent "whereness" of each other across those them, as well as the grammatics to self-evolved these spaces and how to represent "location" in them. 
Gamez: Provides a place to design and play arbitrary board games. 
WaterTable: Provides ability to create database-like tables for collecting and viewing data. Think of this as an "AirTable" clone! 
Xylem: Provides real-time collaborative spread-sheets based on the Univer open-source library. Moss development is in pre-alpha. It is best suited for adventurous early-adopters. Please don't expect it to be stable or bug free! That said, we use Moss in-house daily for doing our work on Moss itself, using the tools for planning, chatting, video calls, etc.
Expect new versions in which you will have to recreate your groups and recreate your Tool configurations. We export data from our tools frequently and sometimes have to recover from these backups. We recommend you do the same.
We hope you enjoy getting in the game early!
Moss