Current Defaults
Crossbows are priced and unlocked as rifles, and a version exists for all 5 tiers.
Crossbows provide a small infiltration time reduction

Crossbows have 4 available unique attachments:
Skirmisher Frame = Increased flanking crit chance, bonus crit damage
Reaper Frame = Reduced Detection Radius, bonus damage while concealed
Templar Frame = Bonus Ablative Shielding, Bonus Damage against Psionic enemies
Marksman Frame = Bonus to hit and crit if the soldier did not move on the previous turn, bonus damage from high ground

Currently the crossbow included 6 proving ground projects:
Saboteur Bolt Set = Provides access to build 3 explosive bolts
Assassin Bolt Set = Provides access to build 3 single target bolts
Disruptor Bolt set = Provides access to build 3 AOE status effect bolts
Bombardier Bolt Set = Provides access to build 2 anti-environment AOE bolts
Quiver Project = allows building quivers which can contain multiple bolts
Plating Project = allows building unique plating items that provide additional uses for bolts

Crossbows have range bonuses up to about range 12, and then steeply fall off on aim quality beyond that.

Crossbows have a low or non-existent environmental sound impact, so shooting it will not put distant enemies on alert

Crossbows are slow weapons with terrible action economy and do not interact with most 'standard shot' skills. However the Hit and Run ability, Snap shot ability, and a few other common abilities will still work.

This crossbow currently can be used with amalgamation classes.

The classes enabled by default are:
ShadowOps_recon_lwotc
ShadowOps_Hunter_lwotc
LWS_Agent
Reshi's ARFMScavenger
Reshi's ARFMMiner
Captain Pet Rock's Saboteur
Captain Pet Rock's Marksman
The Lwotc Shinobi
Reaper

The unique bolts vary in effectiveness but are intended to be situational solutions for various common situations - there are probably a lot of min/max considerations and soldier skill interactions I did not factor in, so please provide feedback with anything that should be buffed or nerfed - but nearly everything is exposed to config so you should be able to make changes to most of the things that might need adjusting.