menacing

black, bleak, cheerless, chill, cold, comfortless, dark, darkening, depressing, depressive, desolate, dim, disconsolate, dismal, drear, dreary, forlorn, funereal, gloomy, glum, godforsaken, gray (also grey), lonely, lonesome, lugubrious, miserable, morbid, morose, murky, saturnine, sepulchral, somber (or sombre), sullen, wretched

discouraging, disheartening, hopeless, unfavorable, unpromising, unpropitious

ill-fated, ill-starred, star-crossed, troubled, unfortunate, unlucky

evil, malign, malignant

dicey, insecure, precarious, treacherous, uncertain

ultrahazardous

chance, haphazard, random

adverse, bad, baleful, baneful, deleterious, detrimental, evil, harmful, hurtful, ill, inimical, injurious, malignant, nasty, noxious, pernicious, pestilent

deadly, deathly, destructive, dire, fatal, fateful, lethal, mortal, murderous