There is any sistem where playing necromancer is fun?

You can play evil characters in D&D

Also just play with a group that throws out all the good/evil spells stuff.

Playable Necromancers in Dungeons and Dragons 3.5e?
For official base classes, we have:
-Wizard Necromancer (school specialist)
-Three variants of the Necromancy specialization in Unearthed Arcana including either a Skeletal Minion, Undead Apotheosis, or Enhanced Undead as a class feature.
Please note, that 'Van Richten's Guide to Lich' states that liches are no longer limited to their dropped schools of magic if they were specialists in life, so that's something to look forward to.
-The Wizard Necromancer Variant in Dragon 357's Unversed Arcana - The School Mastery variant for Necromancy, swapping out getting familiar for casting chosen school spells at +1 caster level, and all undead madde with [evil] descriptor spells gaining temporary HP equal to your caster level, combine with Enhanced Undead's swap out extra spells per day as a specialist for +2 to STR and DEX and HP per HD in Undead you make, and you've a very decent Necromancer Wizard to use.
-The three 'Dark Magi' Necromancer base classes from Dragon Magazine 312, Deathwalker, Fleshcrafter, and Soul Reaper.
-The Dread Necromancer from Heroes of Horror, popular choice solid class to level 20 and provides base Lichdom as a class feature.
-The Death Master base class (Orcus followers only) from the Dragon Compendium Volume 1. Provides base Lichdom as a class feature.
-A Cleric with some of the following Domains
>Death, Deathless, Deathbound, Decay, Envy, Evil, Hunger, Undeath, Undead, Vile Darkness (referred to as a Darkness domain but is different), Gluttony, Corruption, Repose, Repose(2(there's a second one of this)) Spirit, Pestilence, Necromancer (Blood of Vol) and the seven deadly sins domains.
-The Binder class with choice vestiges such as Acererak, Tennebrous, and some other vestige I don't know about (Tome of Magic).
-The Spellcaster class from Unearthed Arcana (non-descript class built around bonus feats and not class features, build appropriately).

-Nightstalker (Dragonlance - Races of Ansalon)

d20 unnoficial base classes
-Necromancer class from 'Secret College of Necromancy' by Greem Ronin Publishing
-Flesh Mage from Sourcebook, 'Magic' (d20, AEG, 2002).pdf

For official Prestige Classes (PrC) we have:
-Thrall of Orcus (Book of Vile Darkness).
-Walker in the Wastes (Sandstorm) Provides Dry Lichdom, which is basically being a Tomb Kang n sheeit, multiple cheaper phylacteries at the cost of longer rejuvanation time, can literally harvest limitless salt and use infinite pocket sand with this PrC.
-Pale Master (Tome & Blood - Libris Mortis) Suitored to Arcane necromancy users or in choice builds, is easy to get fluff wise, and useful becase fuck black onyx. I also suggest using it's hombrew remake which features some of it's qualities shown in Dungeons and Dragons Online dnd-wiki.org/wiki/Pale_Master,_Rebuild_(3.5e_Prestige_Class) This PrC also has an epic level variant, mentioned fucking somewhere.
-Fleshwarper (Lords of Madness) Mad science so hard you go fullblown aberration, graft dead people to yourself!
-Red Wizard of Thay (In campaign perks of regional feats and background should apply).
-Master Specialist (Necromancy) (Complete Mage).
-Necrocarnate (Magic of Incarnum PrC, is shit).
-Master of Shrouds (Libris Mortis) control of incorporeal undead, maximize ghost blowjobs.
-Tennebrous Apostate (PrC for Binders that use the Tennebrous vestige).
-Soul Eater (Book of Vile Darkness) self explanatory.
-Dirgesinger (Libris Mortis) summon undead with guitar solos.
-True Necromancer (Libris Mortis) don't ever use this.
-Horned Harbinger (FR Faiths and Pantheons) Undead Army Maker
-Companion of the Dead (Gnomish Class with progression unto undeath)
-Darklight Wizard (Kingdoms of Kalamar Villain Design Handbook)
-Death Dancer (Kingdoms of Kalamar Stealth and Style) Thriller.
-Lady/Lord of the Dead (Web Enhancement - Dead Life)
-Blighter (Masters of the Wild, Complete Divine) Anti-druid

archive.is/fRAn3 - K's Necromancer Revised handbook

wizards.com/dnd/article.asp?x=dnd/dx20021031x - Dead Life
archive.wizards.com/default.asp?x=dnd/sp/20031212a - Lich Monster class progression

Important Orcus Stuff-
TSR 2005 - Supplement III - Eldritch Wizardry.pdf Page 35
TSR 2009A - Monster Manual.pdf page 17
TSR 1017 - Set 5 Immortals Rules.pdf Page 31 (Ability mentioned under control undead carried on to 3e-3.5)
TSR 9228 - H4 - The Throne of Bloodstone.pdf (Entire module, notable the content on his wand, features of his layer (number and name was changed in later editions, but choice minions and almost all of the landscape features carried on, next to being the module you need to refer to for most cases of layout) Orcus on Page 76
Dead Gods (Canon, important to note is the person who resurrects him as he reoccurs, the balor from throne of bloodstone is here, and the orcussword was updated to 3.5, Important for context on undead Visages alter reality powers as they are statted in Libris Mortis also)
Dungeon magazine #089 (First released 3e statblock alongside a questline with him, notably one of the three most powerful released, featuring a return of his old 1e Control undead ability, and afew other things you want to keep track of for his other statblocks such as how he casts spells relating to his progression to demon lord featured in Dead Gods being taken into account (Was a Cleric/Wiz before death and rebirth) mentions his domains and that he is a specialist but suffers no prohibition to spell schools)
Book of Vile Darkness (Page 136, noted for the fact that Orcus can also presumably use Spells limited to Undead (A reference to the like of Lichspells from Ravenlofts Van Richten's Guide to the Lich and other Necromancy descriptor spells specifically fluffed for the undead, and gives him a cap on divination that makes no sense)
Fiendish Codex 1 & it's W-E p73 &19 (Incredibly weak quick-dungeon friendly Orcus, actually has much less at his disposal and isn't even accurate in terms of abilities held, Use the aspect, ditch the main one, as all D&D3.5 Demon lords received their actual correct statblocks in dedicated Dragon Issues.

Dungeon #149 P56-57 Updated Findiesh Codex Orcus statblock complete with Auras, the last word, and far more accurate statistics.

As for how he casts spells, using his 3e-3.5 statblocks and what is accurate to him lore-wise
we have-
Cast spells as a Cleric (15) Necro (20) (Has no prohibited schools, can cast spells limited to Undead, treats clerical spells as arcane as to bypass need for a divine focus, has access to the Chaos, Death, Destruction, and Evil Domains)
Though technically he also has access to the Vile Darkness Domain due to his time as Tennebrous (is referred to as the Darkness (2) Domain in write-ups) And the Spirit domain per it's mention in Dragon Magazine for any patron who deals in soul theft and similar acts that violate the afterlife

>necromancer
Demons>>>>>>skeletons

Oh right, Ghostwalk, as he's a deity in that one, and it probably predates Dead Gods timeline wise.

as cool as necromancers are and as cool as they can be to fight against, player characters with tons of pets/summons/reanimated dead really tend to bog down combat in games like d&d

hard to get them right

AFF2e gives necromancers light sabers for 1 MP.

d&d is shit
muh hp
systens that handle health as injuries are better

Grim World's necromancer class is all about building undead abominations. Not just swarms of zombies, full on venomous winged dire bear shit.

Here's your (you).