Achievement	Engine/Game	Why it's bad
storing world space positions in gbuffer	STALKER, F.E.A.R.	Depth buffer can be used to derive position saving a lot of memory bandwidth
uploaded texture upside down	Various engines, mostly Quake derived.	Difficult to debug with tools like apitrace, nsight, pix, renderdoc, etc
fixed function pipeline on top of a single vertex buffer	Tesseract, GoG porting layer	Inefficent use of modern rendering since you need to stream data every frame
made your own texture compression format that works with the driver's decoder somehow	Darkplaces (S2TC)	To avoid S3TC patents which are now expired
cleared color, depth and stencil buffers individually	idTech4, Unity	Clearing them individually is slow path in driver, all at once is optimal
line rendering with quads	Various	Less efficent and don't get hardware assisted AA like line rendering gets
per-vertex lighting	Cube, Minecraft, Gears of War, Skyrim	Looks very bad compared to lightmaps and or realtime lighting
used facet normals	Goldsrc, UE2, UE3	Looks very bad compared to smooth normals, lighting will be incorrect
manual gamma correction on sRGB textures	Various	Incorrect and defeats the purpose of sRGB assist
used degenerate vertices to build triangle strip	UE1, Goldsrc, Source, Witness (lightmap mesh parameterization)	Degenerate vertices can lead to rendering artifacts depending on hardware
used separate vertex buffers for vertex attributes	Frostbite, idTech3, idTech4, UE3, UE4	Interleaved data is more efficent
blamed it on the driver	Every engine	Wastes time
"fixed" shadow acne with subnormal bias	Irrlicht, Godot, Serious Sam	Floating point precision can lead to rendering artifacts
surface area heuristic uses hyperbolic functions	Irrlicht, Frostbite	Geometry is Euclidean not hyperbolic, this is just completely wrong
scene graph is a linked list	GL Quake, Serious Sam	Not very cache efficent
mixing audio in render loop	Win Quake, GL Quake, qfusion (Warsow)	Ties audio mixing to framerate and hitches in rendering can cause audio aliasing
blocking on hardware occlusion queries	Various	Defeats the purpose of culling (to speed things up; blocking is the opposite)
skeletal animation done in scripting language	Total Annihilation, Natrual Selection 2, Unity	Skeletal animation is expensive, why would you do it in non-native code?
wrote a geometry shader	Various "AAA" engines	Often slower than just feeding data from CPU due to how HW implements them
environment mapping using different sky texture	Various	Reflections are incorrect
block-compresssed tangent space normal maps	Various	Normal maps break when block-compressed
font rendering with texture per-glyph	libass, Gutair Hero III	That's a lot of textures and texture binds
wrote SIMD for unaligned data	idTech3, idTech4, Darkplaces, others	Processing unaligned data is slower than aligned and often slower than scalar
integrated Scaleform	Wayforward, CryEngine, XCOM2, Several others.	Scaleform is huge and crashes linkers, it's also full of bugs, don't use it
shipped a debug build	Skyrim	Debug builds run slower and often contain source code
shipped with debugger because it didn't crash in debugger	Wing Commander (sort of)	No time to fix a bug
modified debugger exception to hide a crash	Wing Commander	But time to hide it
compiled with -ffast-math and physics became more interesting	Anything which uses Bullet.	Bullet depends on subnormals and other strange float quirkyness to work
issued hardware occlusion queries for the HUD	Stardock (Galactic Civilizations)	The HUD is always visible why issue queries for it?
render functions are virtual	UE3, UE4, CryEngine	Virtual dispatch on different renderables is not cache friendly
glReadPixels without a PBO	Various	Blocks the render thread and forces a syncronization, i.e causes a hitch
destroyed render resources after deleting graphics context	Various	Undefined behavior
wrote software rasterizer because driver kept crashing	Epic (UT99) (Pixomatic)	Impressive but also a huge waste of time and technical debt
level stored in XML	Various tile/side-scroller games	XML is the worst serialization format for levels
shipped dedicated server bins for s390x only	Battlefield 1942 (x86 came later)	No one has s390x hardware
game scripting language requires a SAT solver	Mono scripting (C# requires SAT)	SAT solving is expensive and confusing
engine depends on Qt	Wayforward, Doomsday	Qt is a massive runtime dependency
hybrid shader language built ontop of macros targeting GLSL and HLSL	Source 2 (togl), Doom 3 BFG, RAGE	The readability of Perl
debug build is slower than running release build in valgrind	Neothyne	Valgrind emulates x86, imagine debug native slower than release interpreted
incremental GC is called when player takes damage	Several shipped RenPy and Love2D games.	Need to hide the GC pauses somewhere
in game updater uses bittorrent	WoW, Halo3 for PC.	Too cheap to host distribution so saturate everyone's internet instead
in-house developed SWF renderer	Doom 3 BFG, RAGE	SWF has embedded Actionscript
added whitespace because asset hashed to the same hash as another asset	Spyro: Enter the Dragon	Not enough time to replace the hash function
engine (or engine components) are shared libraries	Source 2, Godot, Irrlicht	Waste of development time to maintain builds and offers no real benefit
actually did something about "half pixel offset" in D3D that made things worse	Unity	Waste of development time to fix something that only made things worse
used both OpenGL and D3D at the same time	CryEngine (Compute was GL)	Impressive but also requires extensions to share resources between contexts
Ported to OSx and Linux by writing a D3D to OpenGL "porting layer"	CryEngine, Source	The time to develop that surely must've been more than just writing a GL backend
Physics simulation fixes T-junctions in meshes each physics step	CryEngine	It's possible to simulate without making T-junctions to begin with
Syncronization primitives implemented with shared memory and files (File system sync)	CryEngine	Using file IO to syncronize code
User interface is a webbrower	Tabletop Simulator, Overgrowth, GTA V, Several others.	Massive dependency full of security holes
Allocates all of system memory	Various	Waste of virtual address space makes context switching overhead more expensive
Input event processing on audio thread	Bioshock Infinite	Audio heavy scenes drop input events randomly
IPC using flat files on disk	XCOM	File explosion
Oblique frustum is actually a cylinder	Starsiege: Tribes	Doesn't work and causes culling issues
SIMD math code using virtual functions	No Man's Sky, Doom 3 BFG	Virtual dispatch breaks pipelining of SIMD on some older microarchitectures
Serialized entity state as separate files (with more open FDs than a default install supports)	ARK: Survival Evolved	File explosion and requires ulimit adjustments to work on Linux due to FD limit
native Linux/MacOS OpenGL port runs slower than Windows version in Wine	Source, Source2, Minetest	Bad port
shipped with assertions enabled	Shovel Knight	Makes things slower and can cause confusion for users if one triggers
bootstraps itself just so it can render its own icon set	Houdini	Excessive masturbation
creates temporary files to format strings, which is then used as keys to reference objects	CryEngine	File io to format strings and also lookup hashtable values by key
reference counted pointers for simple value types like vectors and events	Godot	Unnecessary
everything inherits from a base object type	Godot, UE, UE2, UE3, UE4, CryEngine	OOP spelt backwards is POO
decided to use a lesser supported graphics API than the one they wanted to use	Godot	Tons of extension wrangling that is buggy and requires driver workarounds