Days autism

Game timeline: 351 days (begins on Day 7)
1 mission = 1 day

Total playable days: 93
Total optional days: 33
Cutscene-only days: 3
Conclusion: Story only takes ~17% total timespan
35% of game content is optional

Breakdown of mission types:
Tutorial: 6 (6.4%)
Collect hearts: 16 (17%)
Eliminate X: 38 (40.8%)
Collect Organization emblems: 4 (4.3%)
Destroy the shadow globs: 4 (4.3%)
Investigate X: 5 (5.3%)
Vanquish the Heartless threat: 5 (5.3%)
Other: 15 (16%)

Stealth segments: 8

Mission locations:
The World That Never Was: 5 (5.3%)
Twilight Town: 25 (26.8%)
Agrabah: 14 (15%)
Beast's Castle: 13 (13.9%)
Olympus Coliseum: 8 (8.6%)
Halloween Town: 10 (10.7%)
Wonderland: 10 (10.7%)
Neverland: 8 (8.6%)

Total Heartless species: 88
Subspecies (recolors): 60 (68%)
New species: 10 (11%)

Total Roxas coma time: 24 days
Total Xion coma time: 21 days
Total Xion missing time: 43 days

Ice cream days: 41/60 (68%)
8, 14, 15, 22, 23, 24, 25, 71, 72, 73, 74, 75, 94, 95, 96, 97, 117, 118, 119, 120, 149, 150, 151, 152, 153, 154, 171, 173, 174, 194, 195, 224, 225, 255, 256, 276, 296, 297, 321, 322, 352
All 33 optional days end with a short scene of Roxas eating ice cream on the clock tower.

Character appearances (speaking/relevant) [silent partners not counted] [Saïx not counted as mission interface]:
[Days in brackets are cutscene-only and not counted in percentage (based on playable days)]
Xemnas: 7, 26, 94, 256, 299, 322, 354, 356, 357 (9.6%)
Xigbar: 24, 26, 71, 117, 149, 224, 256, 321, 322, 353, 354 (11.8%)
Xaldin: 26, 119, 149, 150, 171, 256, 299, 354 (8.6%)
Vexen: 12 (1%)
Lexaeus: 13 (1%)
Zexion: 10 (1%)
Saïx: 23, 25, 26, 51, 72, 75, 94, 96, 117, 150, 172, 193, 255, 256, 297, 298, 299, 322, 352, 353, 354, 355, 357 (24.7%)
Axel: 7, 8, 14, 22, 23, 71, 72, 73, 74, 75, 94, 95, 96, 117, 118, 149, 150, 151, 152, 154, 171, 172, 173, 174, 193, 194, 195, 224, 225, 255, 256, 276, 296, 297, 298, 299, 300, 321, 352, 353, 354, 355, 356, 357 (47.3%)
Demyx: 24, 26, 71, 117, 149, 153, 224, 256, 354 (9.6%)
Luxord: 172, 194, 255, 299, 354 (5.3%)
Marluxia: 9 (1%)
Larxene: 11 (1%)
Roxas: all (player) [49, 50]
Xion: 7, 8, 23, 25, 74, 75, 76, 94, 95, 96, 117, 118, 119, 149, 150, 151, 193, 194, 195, 224, 225, 255, 276, 297, 298, 299, 300, 321, 352, 353, 355, 356, 357 [49, 50] (35.4%)

Riku: [149, 150, 151]* 276, 297, 299, 352, 353, 354, 358 (8.6%)
*"Sham" scene at Beast's Castle
Mickey: 354 (1%)
Naminé: 26, 95, 193, 224, 276, 300, 352, 356 (8.6%)
DiZ: 95, 224, 300, 352, 356, 358 (6.4%)
Pete: 72, 75, 195, 300, 301 (5.3%)

Grey Area appearances [optional days are unchanged from necessary days except removing partners as missions are cleared]:
Xemnas: (0%)
Xigbar: 7, 11, 22, 24, 26, 51, 71, 94, 117, 119, 151, 152, 171, 172, 194, 256, 296, 299, 321, 322, 352 (35%)
Xaldin: 22, 25, 26, 73, 75, 95, 96, 97, 119, 149, 150, 152, 153, 193, 296, 299, 301, 354 (30%)
Vexen: 11, 12 (3%)
Lexaeus: 10, 13 (3%)
Zexion: 8, 10, 13, 15 (6%)
Saïx: all [mission interface]
Axel: 7, 8, 14, 22, 72, 73, 74, 75, 94, 95, 96, 97, 150, 151, 171, 173, 193, 194, 224, 225, 277, 296, 297, 298, 301, 322, 352 (45%)
Demyx: 9, 12, 14, 23, 24, 26, 51, 71, 72, 74, 97, 117, 152, 153, 171, 172, 173, 224, 225, 256, 277, 354 (36%)
Luxord: 15, 22, 24, 73, 74, 117, 119, 151, 153, 172, 173, 194, 255, 256, 277, 322, 352, 354 (30%)
Marluxia: 9, 10, 13, 14, 15 (8%)
Larxene: 7, 12, 14, 15 (6%)
Roxas: N/A
Xion: 8, 15, 23, 24, 25, 26, 75, 94, 95, 96, 193, 194, 225, 301, 321, 322 (26%)

Borrowed scenes:
Day 24: flashback to Xemnas giving Roxas his name
Day 26: flashback to Day 6, Dark Margin meeting with Xemnas
Day 355: Roxas defects
Day 358: Another Side, Another Story... [deep dive] recreated (with Xion), KHII flashbacks to Riku facing Roxas