70. Blood (Monolith, 1997)

The Build engine may have looked just a bit dated by 1997, especially since Quake was the hot new game on the market, but Blood proved that superior design could more than make up for older tech. Blood is a master class of horror elements, with a grim, creepy atmosphere and enemies like giant spiders, gargoyles, cultists and flame-spewing cerberus dogs, all with the same immersive and surprisingly realistic level design that made Duke Nukem 3D work so well. The weapons are equally inventive, with mundane options like a shotgun and tommy gun taking a back seat to weapons like a flare gun or a spray can/lighter to ignite enemies, a voodoo doll that inflicts extra damage to undead/magical enemies (but will damage you if you stab it when no enemies are onscreen) and a crazy-looking skull staff called the Life Leech that doubles as a stationary sentry gun. The game was exceptionally tough (not aided by a bug that would cause the difficulty level to cycle every time one loaded a save), but the sheer inspiration behind its design is something that must be seen. It's just a shame the sequel (Blood II: The Chosen) was such a mess. As for the sequel's expansion... well, "avoid at all costs" is about the kindest thing that can be said for that.
69. Scorched Earth (Wendell Hicken, 1991)
At a glance, Scorched Earth isn't much to look at - a game with tiny sprites and simplistic VGA graphics where tanks shoot missiles and try to blow each other up. But then you take a closer look and find that this game is steeped in clever mechanics and surprisingly deep tactics. From MIRVs to Funky Bombs to Sandhogs, the game has a variety of interesting weapons to utilize, some of which can devastate everything on the screen (even their user) in short order. Further adding to the fun are defensive items like shields and options like having shots wrap around to the other side of the screen, bounce off the ceiling or radically shifting winds making aiming shots more difficult. In short, it's a game with a lot of options and endless replayability, especially in multi-player combat. The only real crime is that it never got an online play option!
68. Heretic II (Raven Software, 1998)
Most people know about Heretic, but not too many people know it had a sequel. Mostly because it didn't sell particularly well and owing to a dispute over rights to the game, it has not resurfaced on any digital distribution stores. Which is a shame, as it's quite a unique and fun experience in its own right. A third person action game that takes a few cues from Tomb Raider, with some polished platforming mechanics and a bit of focus on puzzle solving. It doesn't lose sight of what made the original popular, though - after all, it's built in the Quake II engine, which lends itself perfectly to fast-paced projectile-slinging action against hordes of monsters. Even melee brings some clever mechanics, with sweeping blows that deal heavy damage (and gory finishers) to enemies and even letting you use your staff to pole-vault, which both serves as a longer jump and a powerful mobile attack. Heretic II is far less famous than its predecessor, but no less fun.
67. Heretic (Raven Software, 1994)
As popular as Doom was, it was little surprise that it would get a number of spinoff games and engine licenses. Heretic is definitely one of the more memorable ones, taking the basic monster-blasting, puzzle-solving format of Doom and putting a coat of dark fantasy on everything. Golems, axe-throwing skeleton knights, sorcerers and demons, among many others, stand in your way, while you get several weapons like a magic staff, a triple-firing crossbow, a fireball-launching mace and my personal favorite, gauntlets that launch lightning at your enemies. More than that, though one could actually pick up many powerups and use them when needed, rather than being forced to activate and use them right then and there. From temporary flight to powering up all of one's weapons to simply restoring a bit of health on-demand, they were all quite handy to have.
66. Cave Story (DÅkutsu Monogatari) (Pixel, 2004)
With the internet's explosion in popularity came an interest in indie games old and new, with sites like Newgrounds giving a lot of developers and fans a place to show off their talents and numerous abandonware sites archiving obscure and forgotten classics. Cave Story is one that came to peoples' attention not long after its initial release in 2004, garnering a lot of attention for its high quality Metroid-like design, presentation reminiscent of 8 and 16-bit retro titles, having a surprisingly engrossing story and being created over the course of five years by a single developer. Since then it's gotten tons of attention in the form of fan translations, ports to numerous platforms (official and otherwise), a slew of remakes, mods and source ports, and even a fan-created level editor.
65. Commander Keen in Goodbye Galaxy! (id Software, 1991)
The fifth and sixth parts of the Commander Keen series (though labeled as 4 and 5... it's complicated) were a big leap forward for not just platformers on the PC, but for the series itself. Smooth-scrolling, fluid platforming action was almost unheard of in DOS games at the time (compare this to say, Duke Nukem 1 or the Mega Man DOS games - BIG difference!), and the level of graphical detail was sublime and imaginative, looking like a cartoon on your computer. Many of Keen's trademark elements return - the stun gun, the pogo stick and tons of collectibles - but the smoother controls and new capabilities like climbing up poles, unlocking rooms with keycards and mantling up ledges made its gameplay both more fun and more complex than previous entries. He may not be as well-known as Sonic or Mario, but Keen was the closest thing the PC platform had for a good, long while.
64. Abuse (Crack dot Com, 1996)
A run-and-gun shooter that plays like one part Contra, one part Doom and one part Smash TV, Abuse was like nothing else on PC at the time. Basically a 2D platformer with 360-degree movement and aiming via the mouse, the game took advantage by having enemies be fast and ruthless and come at you from every angle, quickly overwhelming you if you weren't careful. Of course, it also took cues from games like Doom with multiple hidden secrets and powerups to find in each stage and even a few alternate pathways to discover. Its source code has also been released, allowing it to get ports to multiple platforms, so there's no excuse to not check out Abuse.
63. The Dig (LucasArts, 1995)
Another adventure title from the legendary LucasArts, though unlike most, The Dig doesn't have a lot in the way of the company's quirky humor, opting to tell a more somber, serious and high-concept science fiction story. Starring a team of scientists unexpectedly whisked away to an alien world devoid of intelligent life but full of advanced technology, they set out to uncover exactly what led it to its current state and discover a way home. The Dig was also a very high-end production for its time, having surprisingly well-known actors voicing the main characters and some incredible atmospheric music by Michael Land.
62. The Curse of Monkey Island (LucasArts, 1997)
The Monkey Island series is a beloved classic among adventure game fans; following the exploits of the bumbling wannabe-pirate Guybrush Threepwood, he seeks to win the affections of Elaine Marley and frequently clashes with his nemesis, the evil undead pirate LeChuck. Curse took the series in a bold new direction with a fresh visual style, plenty of animated cutscenes and perfectly cast voiceover complementing the humor throughout. The scenarios are as absurd as ever - this time with Guybrush trying to reverse a voodoo curse he's unintentionally afflicted Elaine with - and that of course lends itself to plenty of laughs. The interface was newly reworked too, using a simpler "verb coin" with three general commands instead of the array of commands from earlier SCUMM games. The puzzles definitely didn't suffer for it, though - you're still in for a challenge, especially in "Mega Monkey" mode.
61. Loom (LucasArts, 1990)
Another excellent point-and-click adventure from LucasArts, Loom takes the player on a trip through a wonderfully-realized dark fantasy world full of striking visuals, dense lore and an unforgettable cast of characters. Some surprisingly unique mechanics, too, as you don't really follow the usual pick-up-an-item-and-use-it-elsewhere format seen in most games of this type. Instead, you utilize Bobbin's distaff and play magical 'drafts' with a variety of effects; turning straw into gold, opening things, dyeing objects, and so forth, and often you can play them backwards to get the opposite effect (though some are palindromic and thus cannot be used this way). Some inspired voiceover and detailed VGA visuals (for the later versions) completed the package and made it a delightful experience.