Assets are distributed under their original licenses:

chest/*: Luxology Modo (https://emackey.github.io/testing-pbr/)
firehydrant/*: Substance Share (https://substance3d.adobe.com/community-assets/) Creative Commons 4.0 (https://emackey.github.io/testing-pbr/)
cursors/*: Kenney (www.kenney.nl) Creative Commons Zero, CC0. 
tank/*: "Tank Low-Poly # 2" (https://skfb.ly/oEHOR) by Sidra is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
gate/*: "Mojo Barrier" (https://skfb.ly/ovnYu) by Sousinho is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
pressure_plate/*: "Button" (https://skfb.ly/o6s7M) by Kacper "Papysh" Żurawski is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
light_floor/*: "SciFi Light 15" (https://skfb.ly/6nBPF) by inuhitman is licensed under Creative Commons Attribution-NonCommercial (http://creativecommons.org/licenses/by-nc/4.0/).
barracks/*: "Barracks" (https://skfb.ly/66vCG) by Oakioats is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
tiling/*: https://3dtextures.me (João Paulo) and https://freepbr.com.
turret/*: "Auto Turret Machine Gun" (https://skfb.ly/oysBt) by NghiaNguyeen is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
barrel/*: "Old tin barrel" (https://skfb.ly/6A8Io) by 3dhdscan is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
barrel_explosive/*: "Flammable Barrel" (https://skfb.ly/oGpVz) by RRFREELANCE is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
crate/*: "Crate box" (https://skfb.ly/RMpW) by KloWorks is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
tent/*: "Military Tent" (https://skfb.ly/o6pP7) by Thunder is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
rock/*: "Lowpoly Rocks - 3" (https://skfb.ly/6yTQs) by Loïc Norgeot is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
water_tower/*: "Free - Water Tower" (https://skfb.ly/oovr7) by Emanuel is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
container/*: "Shipping containers" (https://skfb.ly/oCSOU) by Mateusz Woliński is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
car_wreck/*: "Reliant K Car" (https://skfb.ly/otqDo) by Renafox is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
tree_acacia/*: "Acacia tree" (https://skfb.ly/ouYrM) by evolveduk is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
plant_fern/*: "Fern" (https://skfb.ly/o99LX) by evolveduk is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/)..
buddha.obj: Downloaded from Morgan McGuire's Computer Graphics Archive: https://casual-effects.com/data
bunny.obj: Downloaded from Morgan McGuire's Computer Graphics Archive: https://casual-effects.com/data
dragon.obj: Downloaded from Morgan McGuire's Computer Graphics Archive: https://casual-effects.com/data
head/*: Downloaded from Morgan McGuire's Computer Graphics Archive: https://casual-effects.com/data
pedestal/*: https://www.cgtrader.com/free-3d-models/exterior/historic/pedestal-85833ed1-f33d-41bb-8454-c4f4a6189d42
corset/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Corset
boombox/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/BoomBox
antiquecamera/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/AntiqueCamera
normal_tangent_test/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/NormalTangentTest
normal_tangent_mirror_test/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/NormalTangentMirrorTest
rigged-simple/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/RiggedSimple
fox/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Fox
suzanne/*: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Suzanne
testimages/*: https://testimages.org/ (https://sourceforge.net/projects/testimages/)
cayo/*: All rights reserved, no redistribution allowed.
terrain/*: Gaea (https://quadspinner.com/) and WorldMachine (https://www.world-machine.com/) both licenced.
fence/*: "Fences | Concretes | Metal | Desert | Old | Pack" (https://skfb.ly/o7CxG) by YadroGames is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
vanguard/*: https://www.mixamo.com/
swat/*: https://www.mixamo.com/
maynard/*: https://www.mixamo.com/
skybox/sorsele_*: Emil Persson, aka Humus. http://www.humus.name
skybox/teide_*: Emil Persson, aka Humus. http://www.humus.name
vfx/flash.tga: https://toppng.com/
vfx/flash_star.tga: https://toppng.com/
vfx/flash_star.tga: https://toppng.com/
vfx/heat_distortion*: https://andrewgotow.com
fire/*: https://www.filterforge.com/
gas_tank/*: "Gas tank" (https://skfb.ly/6zZpP) by Wafelek is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
tires/*: "Muddy tire" (https://skfb.ly/69IZM) by Fabian van Dorst is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
alarm/*: "Urban Communications - Low poly prop set" (https://skfb.ly/oyGXB) by Daniel Zhabotinsky is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
traffic_signs/*: "Trafficstuff" (https://skfb.ly/oo9DF) by Thunder is licensed under Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/).
decals/text_volo.tga: https://www.fontspace.com/misdemeanor-font-f16218
decals/scorch.tga: http://www.imarvintpa.com/
decals/explosion.tga: https://www.pngkit.com/bigpic/u2q8a9a9t4o0e6t4/
sound/tank-idle-01.wav: By 'Pixabay' from Pixabay https://pixabay.com/sound-effects/bus-engine-idling-26992/
sound/tank-move-01.wav: By 'DennisH18' from Pixabay https://pixabay.com/sound-effects/tank-moving-143104/
sound/tank-shot-01.wav: By 'Pixabay' from Pixabay https://pixabay.com/sound-effects/tanks-shooting-33651/
sound/tank-turret-01.wav: By 'Pixabay' from Pixabay https://pixabay.com/sound-effects/tank-turret-rotate-14879/
sound/ambiance-01.wav: By 'Isaac200000' from Pixabay https://pixabay.com/sound-effects/ambiance4-31974/
sound/blinded-by-the-light.wav: By 'KELLEPICS' from Pixabay https://pixabay.com/music/electronic-blinded-by-the-light-13359/
sound/gun-01.wav: By 'morganpurkis' from Pixabay https://pixabay.com/sound-effects/single-gunshot-62-hp-37188/
sound/gun-02.wav: By 'nioczkus' from Pixabay https://pixabay.com/sound-effects/m1-garand-rifle-80192/
sound/gun-03.wav: By 'morganpurkis' from Pixabay https://pixabay.com/sound-effects/single-gunshot-54-40780/
sound/gun-04.wav: By 'nioczkus' from Pixabay https://pixabay.com/sound-effects/m1-garand-rifle-80192/
sound/gun-05.wav: By 'morganpurkis' from Pixabay https://pixabay.com/sound-effects/single-gunshot-54-40780/
sound/death-01.wav: By 'Albasty' from Pixabay https://pixabay.com/sound-effects/monster-sound-medium-death-94826/
sound/death-02.wav: By 'surfaceknight68' from Pixabay https://pixabay.com/sound-effects/monster-chase-grunts-45476/
sound/death-03.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/male-extreme-scream-123078/
sound/death-04.wav: By 'anwul' from Pixabay https://pixabay.com/sound-effects/monster-105850/
sound/swoosh-01.wav: By 'Natty23' from Pixabay https://pixabay.com/sound-effects/whoosh-6316/
sound/impact-01.wav: By 'pixabay' from Pixabay https://pixabay.com/sound-effects/086553-bullet-hit-39853/
sound/impact-02.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/punch-140236/
sound/electric-motor-01.wav: By 'Starscade' from Pixabay https://pixabay.com/sound-effects/sfx-cassette-tape-motor-30698/
sound/burning-01.wav: EpidemicSound: https://www.epidemicsound.com/track/KNTZATADAz/
sound/burning-02.wav: By 'Flame Thrower' from Pixabay https://pixabay.com/sound-effects/flame-thrower-128555/
sound/burning-03.wav: By 'Fission9' from Pixabay https://pixabay.com/sound-effects/lava-loop-3-28887/
sound/launch-01.wav: EpidemicSound: https://www.epidemicsound.com/track/hrrNYY6LoC/
sound/launch-02.wav: 18hiltc: https://freesound.org/people/18hiltc/sounds/202725/
sound/explosion-01.wav: EpidemicSound: https://www.epidemicsound.com/track/a1WjOQpFnP/
sound/explosion-02.wav: By 'frolickingdp1' from Pixabay https://pixabay.com/sound-effects/explosion-6801/
sound/explosion-03.wav: By 'Pixabay' from Pixabay https://pixabay.com/sound-effects/medium-explosion-40472/
sound/indicator-01.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/interface-124464/
sound/indicator-02.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/interface-124464/
sound/click-01.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/click-button-140881/
sound/click-02.wav: By 'UNIVERSFIELD' from Pixabay https://pixabay.com/sound-effects/click-button-140881/
sound/click-03.wav: By 'SennaFoxy' from Pixabay https://pixabay.com/sound-effects/enter-button-mechanical-keyboard-14388/
sound/confirm-01.wav: By 'flobelle' from Pixabay https://pixabay.com/sound-effects/confirmation-noises-94299/
sound/confirm-02.wav: By 'flobelle' from Pixabay https://pixabay.com/sound-effects/confirmation-noises-94299/
sound/confirm-03.wav: By 'flobelle' from Pixabay https://pixabay.com/sound-effects/confirmation-noises-94299/
sound/confirm-04.wav: By 'flobelle' from Pixabay https://pixabay.com/sound-effects/confirmation-noises-94299/
sound/rank-up-01.wav: By 'Pixabay' from Pixabay https://pixabay.com/sound-effects/army-rank-up-2-84543/
sound/announcer-unit-ready.wav: from Pixabay https://pixabay.com/sound-effects/unit-ready-40641/
sound/announcer-*.wav: https://voicemaker.in/ (paid plan)