You can hear the track below.
https://www.youtube.com/watch?v=2YwkmmO0-_Y
You can buy the Determination album below.
https://www.fangamer.com/products/undertale-determination-cd
You can buy the individual tracks below.
https://determination-ut.bandcamp.com/album/determination
You can buy Beat Hazard 2 below.
https://store.steampowered.com/app/618740/Beat_Hazard_2/
...
https://www.youtube.com/watch?v=mAVNMrv6c5U
You can download Valkyrie below.
https://steamcommunity.com/sharedfiles/filedetails/?id=1917713379
You can download Omega Zero below.
https://steamcommunity.com/sharedfiles/filedetails/?id=2557994580
You can download the stage (Omega Showdown) below.
https://steamcommunity.com/sharedfiles/filedetails/?id=2776352336
You can buy Rivals of Aether below.
https://store.steampowered.com/app/383980/Rivals_of_Aether/
...
https://www.youtube.com/watch?v=dXRKbO6U1pc
You can download Solid Snake below.
https://steamcommunity.com/workshop/filedetails/?id=2801695646
You can download BROS below.
https://steamcommunity.com/sharedfiles/filedetails/?id=2021255136
You can download Break the Targets below.
https://steamcommunity.com/sharedfiles/filedetails/?id=2169436552
You can buy Rivals of Aether below.
https://store.steampowered.com/app/383980
...
https://www.youtube.com/watch?v=vAgwezTpmuQ
You can download Missingno. below.
https://steamcommunity.com/workshop/filedetails/?id=2606989921
You can download Boss!Astra below.
https://steamcommunity.com/sharedfiles/filedetails/?id=2239606881
You can download the stage (Ragnarok Core) below.
https://steamcommunity.com/sharedfiles/filedetails/?id=1973485226
You can buy Rivals of Aether below.
https://store.steampowered.com/app/383980/Rivals_of_Aether/
...
https://www.youtube.com/watch?v=10Md4FBalGg
I did this in Last Man on Earth on Easy in the Apartments chapter in the Half-Life 2: Point Insertion & A Red Letter Day campaign. The trick is to hit her after she swings. It should take 4 hits.
You can download the campaign & the required texture pack at the 2 links below.
https://www.gamemaps.com/details/6629
https://www.gamemaps.com/details/6848
You can buy Left 4 Dead 2 below.
https://store.steampowered.com/app/550
...
https://www.youtube.com/watch?v=vzd7095mpOs
This is easily the worst guilt I've ever felt playing a video game & that's despite the fact that I didn't save afterward because this isn't a genocide run.
You can download Undertale Yellow below.
https://gamejolt.com/games/UndertaleYellow/136925
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https://www.youtube.com/watch?v=0dE8IoI_zxA
You can download the track below.
https://www.youtube.com/watch?v=v7BwX9HPDV0
You can download Soundsaber below.
https://sonorousgames.itch.io/soundsaber
You can buy Undertale below.
https://store.steampowered.com/app/391540/Undertale/
...
https://www.youtube.com/watch?v=bH1rBwY1sp0