I had a rly big killing game manga phase over quarantine (like... alice in borderland &...

Tokyo Ravens is a good anime

Idk any killing game mangas, but here are so e shounen/seinen (mostly action) mangas:
https://www.mangago.zone/read-manga/kagurabachi/ (PEAK FICTION)
https://www.mangago.zone/read-manga/gokurakugai/
https://www.mangago.zone/read-manga/windbreaker/
https://www.mangago.zone/read-manga/tokyo_aliens/
https://www.mangago.zone/read-manga/gachiakuta/
https://www.mangago.zone/read-manga/galaxias/
https://www.mangago.zone/read-manga/ghost_fixers/
https://www.mangago.zone/read-manga/centuria/
https://www.mangago.zone/read-manga/psycho_eyes/
https://www.mangago.zone/read-manga/chainsaw_man/
https://www.mangago.zone/read-manga/ultimate_exorcist_kiyoshi/
https://www.mangago.zone/read-manga/madan_no_ichi/
https://www.mangago.zone/read-manga/tongari_boushi_no_atelier/
https://www.mangago.zone/read-manga/magical_girl_and_narco_wars/
https://www.mangago.zone/read-manga/the_marshal_king/

And if you're fine with GLs, try these:
Completed (Fluff):
https://www.mangago.zone/read-manga/the_flower_princess_of_sylph/
https://www.mangago.zone/read-manga/blooming_sequence/
https://www.mangago.zone/read-manga/pink_ribbon/
https://www.mangago.zone/read-manga/half/
https://www.mangago.zone/read-manga/exciting_feelings/
https://www.mangago.zone/read-manga/maison_de_maid/
https://www.mangago.zone/read-manga/the_love_doctor/
https://www.mangago.zone/read-manga/girl_friends/
https://www.mangago.zone/read-manga/mage_demon_queen/
https://www.mangago.zone/read-manga/useless_princesses/
https://www.mangago.zone/read-manga/hana_to_hoshi/
https://www.mangago.zone/read-manga/yume_to_koi_dewa_tsuriawanai/
https://www.mangago.zone/read-manga/bocchi_kaibutsu_to_moumoku_shoujo/
https://www.mangago.zone/read-manga/so_do_you_wanna_go_out_or/
https://www.mangago.zone/read-manga/hello_melancholic/
https://www.mangago.zone/read-manga/teiji_ni_agaretara/
https://www.mangago.zone/read-manga/today_we_continue_our_lives_together_under_the_same_roof/
https://www.mangago.zone/read-manga/sheep_princess_in_wolf_s_clothing/
https://www.mangago.zone/read-manga/crescent_moon_and_doughnuts/
https://www.mangago.zone/read-manga/kimi_ni_tsumugu_bouhaku/
https://www.mangago.zone/read-manga/aoi_hana/
https://www.mangago.zone/read-manga/the_daughter_of_evil_and_miss_devil/
https://www.mangago.zone/read-manga/eventually_i_will_become_yours/
https://www.mangago.zone/read-manga/tsukuritai_onna_to_tabetai_onna/
https://www.mangago.zone/read-manga/still_sick/
https://www.mangago.zone/read-manga/handsome_girl_and_sheltered_girl/
https://www.mangago.zone/read-manga/bead_master/
https://www.mangago.zone/read-manga/ikemen_sugidesu_shiki_senpai/
https://www.mangago.zone/read-manga/dallaeya/
https://www.mangago.zone/read-manga/shoujo_manga_protagonist_x_rival_san/
https://www.mangago.zone/read-manga/hertz_around_you/
https://www.mangago.zone/read-manga/hana_ni_arashi_kovachi_luka/
https://www.mangago.zone/read-manga/how_do_i_get_together_with_my_childhood_friend/
https://www.mangago.zone/read-manga/her_mountain_her_ocean/
https://www.mangago.zone/read-manga/clandestine_affair/
https://www.mangago.zone/read-manga/gal_maid_villainess_only_milady_s_happy_end_will_win/
https://www.mangago.zone/read-manga/akazukin_ni_taberareta_oukami/
https://www.mangago.zone/read-manga/bai_lijin_among_mortals/
https://www.mangago.zone/read-manga/the_noble_lady_on_the_edge_of_the_cliff_wants_to_make_the_dark_knight_fall_in_love/
https://www.mangago.zone/read-manga/odoriba_ni_sukaato_ga_naru/
https://www.mangago.zone/read-manga/ryuu_to_ryuu_no_kekkon/
https://www.mangago.zone/read-manga/shy_na_ano_ko_ni_natsukaretai/
https://www.mangago.zone/read-manga/sherbet_above_the_sea_of_fog/
https://www.mangago.zone/read-manga/koushin_koinu_ni_koibumi_wo/
https://www.mangago.zone/read-manga/cheerful_amnesia/

On-going (Fluff):
https://www.mangago.zone/read-manga/the_moon_on_a_rainy_night/
https://www.mangago.zone/read-manga/yuzu_and_rika/
https://www.mangago.zone/read-manga/the_magical_revolution_of_the_reincarnated_princess_and_the_genius_young_lady/
https://www.mangago.zone/read-manga/gal_loving_jk_wants_to_be_a_gal/
https://www.mangago.zone/read-manga/yuri_yuri_panic/
https://www.mangago.zone/read-manga/makoto_senpai_no_mae_de_wa_kakko_tsukerarenai/
https://www.mangago.zone/read-manga/i_favor_the_villainess/
https://www.mangago.zone/read-manga/watashi_to_kanojo_no_kawaii_koi_no_hajime_kata/
https://www.mangago.zone/read-manga/32_cm_height_difference/
https://www.mangago.zone/read-manga/the_moon_does_not_count_sheep/
https://www.mangago.zone/read-manga/kamiina_botan_yoeru_sugara_wa_yuri_no_hana/
https://www.mangago.zone/read-manga/shinyuu_ni_sukina_hito_ga_dekitarashii/
https://www.mangago.zone/read-manga/big_love_from_ultra_deep_space/
https://www.mangago.zone/read-manga/hanamonogatari/
https://www.mangago.zone/read-manga/yearning_for_a_night_full_of_you/
https://www.mangago.zone/read-manga/the_heart_of_the_thorns/
https://www.mangago.zone/read-manga/tsumugi_chan_wants_to_make_seto_san_laugh/
https://www.mangago.zone/read-manga/furetai_wa_koi_no_hajimari/
https://www.mangago.zone/read-manga/kimi_ga_hoeru_tame_no_uta_wo/
https://www.mangago.zone/read-manga/the_subjugation_school_life_of_the_corpse_girl_and_the_love_heavy_knight/
https://www.mangago.zone/read-manga/girlfriend_limited_to_7_days/
https://www.mangago.zone/read-manga/oni_ure_idol_ga_kyou_mo_watashi_wo_oshitekuru/
https://www.mangago.zone/read-manga/foxes_always_lie/
https://www.mangago.zone/read-manga/adachi_to_shimamura/
https://www.mangago.zone/read-manga/koharu_to_minato_watashi_no_partner_wa_onna_no_ko/
https://www.mangago.zone/read-manga/mietemasu_yo_aizawa_san/
https://www.mangago.zone/read-manga/love_gives_me_superpowers/
https://www.mangago.zone/read-manga/my_ex_girlfriend_became_my_boss/
https://www.mangago.zone/read-manga/unnie_i_like_you/
https://www.mangago.zone/read-manga/wicked_spot/
https://www.mangago.zone/read-manga/akumade_amai_watashi_no_kanojo/
https://www.mangago.zone/read-manga/tsumetakute_yawaraka/
https://www.mangago.zone/read-manga/genjitsu_sekai_real_demo_shiawase_ni_shite_kudasai_ne/
https://www.mangago.zone/read-manga/koi_yori_aoku_oneshot/
https://www.mangago.zone/read-manga/ano_koro_no_aoi_hoshi/
https://www.mangago.zone/read-manga/listening_to_the_stars_bbl_scans/
https://www.mangago.zone/read-manga/muryoku_seijo_to_munou_oujo/
https://www.mangago.zone/read-manga/kiraware_majo_reijou_to_dansou_ouji_no_kon_yaku/
https://www.mangago.zone/read-manga/the_song_that_transcends_this_world/
https://www.mangago.zone/read-manga/anata_mitai_ni/
https://www.mangago.zone/read-manga/ano_ko_to_futari_de/

Completed (Angst):
https://www.mangago.zone/read-manga/run_away_with_me_girl/
https://www.mangago.zone/read-manga/to_die_in_june_one/ (read the last two chapters here: https://www.mangago.zone/read-manga/to_die_in_june/)
https://www.mangago.zone/read-manga/oniisama_e/
https://www.mangago.zone/read-manga/living_will/
https://www.mangago.zone/read-manga/seasons_in_bloom/
https://www.mangago.zone/read-manga/kago_no_shoujo_wa_koi_wo_suru/
https://www.mangago.zone/read-manga/huijin_huayuan/
https://www.mangago.zone/read-manga/vampire_chan_junior_chan/
https://www.mangago.zone/read-manga/yume_no_hashibashi/
https://www.mangago.zone/read-manga/composing_spring_in_this_room_where_cherry_blossoms_bloom/
https://www.mangago.zone/read-manga/kimi_to_tsuzuru_utakata/
https://www.mangago.zone/read-manga/haru_and_midori/
https://www.mangago.zone/read-manga/ohana_holoholo/
https://www.mangago.zone/read-manga/throw_away_the_suit_together/
https://www.mangago.zone/read-manga/getting_to_know_grace/
https://www.mangago.zone/read-manga/i_love_amy/
https://www.mangago.zone/read-manga/the_sound_of_a_butterfly/
https://www.mangago.zone/read-manga/sayonara_rose_garden/
https://www.mangago.zone/read-manga/dark_mermaid/ (bullying, harassment, blackmail, sexual assault [none of these happen between MC and FL])
https://www.mangago.zone/read-manga/this_love_that_won_t_reach/ (age gap, MC is in love with her sister-in-law;rushed and ambiguous ending)
https://www.mangago.zone/read-manga/the_story_of_a_person_who_grew_a_flower/ (short story;age gap, teacher-student relationship;hanahaki disease)
https://www.mangago.zone/read-manga/final_film/ (short story)
https://www.mangago.zone/read-manga/shiroi_heya_no_futari/ (one-shot)
https://www.mangago.zone/read-manga/saudade_ni_kuchidzukete/ (one-shot)
https://www.mangago.zone/read-manga/141108/ (one-shot)
https://www.mangago.zone/read-manga/aliens/ (one-shot)
https://www.mangago.zone/read-manga/the_story_of_the_princess_and_the_little_mermaid/ (one-shot)

On-going (Angst):
https://www.mangago.zone/read-manga/kono_koi_wa_hoshi_ni_wa_negawanai/
https://www.mangago.zone/read-manga/the_wind_spell/
https://www.mangago.zone/read-manga/tower_of_campanella/
https://www.mangago.zone/read-manga/kimi_ga_shinu_made_koi_wo_shitai/
https://www.mangago.zone/read-manga/a_monster_wants_to_eat_me/
https://www.mangago.zone/read-manga/artificial_temperature_36_7_c/
https://www.mangago.zone/read-manga/have_a_great_trip_after_the_credits_roll/

Completed (Smut):
https://www.mangago.zone/read-manga/sadistic_beauty_side_story/
https://www.mangago.zone/read-manga/moonlight_garden_kang_unnie/
https://www.mangago.zone/read-manga/opium/
https://www.mangago.zone/read-manga/kill_switch/
https://www.mangago.zone/read-manga/pulse_ratana_satis/
https://www.mangago.zone/read-manga/just_right_there/
https://www.mangago.zone/read-manga/hateful_lady/
https://www.mangago.zone/read-manga/bad_thinking_diary/
https://www.mangago.zone/read-manga/fly_like_a_butterfly_sting_like_a_bee/
https://www.mangago.zone/read-manga/the_playgirl_and_the_prince/
https://www.mangago.zone/read-manga/the_neighbors_temptation/
https://www.mangago.zone/read-manga/goodnight_cinderella/
https://www.mangago.zone/read-manga/nakayoshi_onna_boukensha_wa_yoru_ni_naru_to_yadoya_de_mechakucha_ecchi_suru/
https://www.mangago.zone/read-manga/club_katoto_chan/
https://www.mangago.zone/read-manga/eat_u_up/
https://www.mangago.zone/read-manga/pet_s_aesthetics/
https://www.mangago.zone/read-manga/office_sweet_365/
https://www.mangago.zone/read-manga/love_does_not_fade/
https://www.mangago.zone/read-manga/umi_to_anata_to_taiyou_to/
https://www.mangago.zone/read-manga/kill_me_now/
https://www.mangago.zone/read-manga/are_you_only_going_to_study/ (age gap)
https://www.mangago.zone/read-manga/talk_dirty_to_me/ (BDSM)
https://www.mangago.zone/read-manga/program_me/ (BDSM)
https://www.mangago.zone/read-manga/suimitsutou_ha_shoujo_ni_kajirareru/ (attempted gangrape on a side character)
https://www.mangago.zone/read-manga/addictive_bing_zi/ (BDSM)
https://www.mangago.zone/read-manga/to_my_neighbor_angel/ (in all chapters except the last two the FL has a dick)
https://www.mangago.zone/read-manga/for_garbage/ (adultery)
https://www.mangago.zone/read-manga/marie_and_alex/ (BDSM)
https://www.mangago.zone/read-manga/damp_ascension/ (one-shot;dub-con)
https://www.mangago.zone/read-manga/hottie_s_heel_uncensored/ (one-shot;BDSM)
https://www.mangago.zone/read-manga/yurika_to_kawakanai_shiitsu_midare_yuri/ (one-shot)
https://www.mangago.zone/read-manga/on_the_promised_night/ (one-shot)
https://www.mangago.zone/read-manga/hidden_meaning/ (one-shot)
https://www.mangago.zone/read-manga/ojou_sama_to_maid_san_ga_yuri_yuri_suru_manga/ (one-shot)
https://www.mangago.zone/read-manga/the_soaking_wet_unnie_next_door_wants_me_to_touch_her_down_there/ (one-shot)
https://www.mangago.zone/read-manga/aki_chan_is_thinking/ (one-shot)
https://www.mangago.zone/read-manga/desire_in_the_dark/ (one-shot)

On-going (Smut):
https://www.mangago.zone/read-manga/asumi_chan_is_interested_in_lesbian_brothels/
https://www.mangago.zone/read-manga/does_it_count_if_your_first_time_is_with_an_android/
https://www.mangago.zone/read-manga/drunken_my_boss/
https://www.mangago.zone/read-manga/love_only_the_body/
https://www.mangago.zone/read-manga/trash_flower/
https://www.mangago.zone/read-manga/please_pick_my_love_too/
https://www.mangago.zone/read-manga/the_wolf_steals_the_sun_athrea_scans/ (dub-con)
https://www.mangago.zone/read-manga/only_to_you/ (BDSM)

GODDAMN

I'm staying for you bro (how long does this even take)

Btw fir the poster, there's 'Kamisama no Iutoori' and 'Real Account'

+1 on Real Account

Omg thanks so much hahaha