Introduction

Portal with RTX is a next-generation remaster of one of the most unexpected runaway successes in PC gaming history. This new version is an effort by NVIDIA to significantly increase the game's realism by leveraging their RTX real-time ray tracing technology, along with support for DLSS performance enhancement, including the latest GeForce Ada DLSS 3 frame-generation. But first, a quick word on the game itself. You are a human test-subject in a science lab that's testing a device that can create point-to-point teleporters. The device itself works like a gun—you aim at a surface (the walls, ceiling, flooring, etc), and shoot the first (source) and second (destination) portals, then pass through them to get from point A to B.

Seems too simple a concept to warrant a runaway success? Wish you'd seen the craze back in the late-2000s when Valve owned game development, and sold episodes of its Half-Life 2 game along with other smaller games in packages such as the Black Box and the Orange Box. Portal mimicked the unexpected success of Counter Strike in the single-player space. Portal with RTX joins a small and [we hope] growing lineup of slightly older games that NVIDIA has taken it upon itself to remaster with ray tracing technology. The last such title was Quake II RTX, another cult-classic, and before that, Minecraft with RTX. These are essentially full-length games that serve as tech-demos to demonstrate the capabilities of path tracing—i.e. a fully ray traced game without any of the hybrid rasterization that's used on all AAA game titles.



Obviously ray tracing and DLSS are things NVIDIA couldn't simply add onto the OpenGL-based idTech 2 game engine for Quake II RTX, and so its remastering involved redevelopment on a whole new graphics API that's aware of the latest technologies. The DirectX 9-based Source engine isn't new enough for these technologies either, and so NVIDIA did something similar—re-developed the game on a newer engine. The company also worked with Valve to remaster the game's various assets—textures, models, etc., so they are higher-resolution and have more detail, including geometric detail. Some of the weighted cubes in the game have been replaced with "Easter egg cubes" that each demonstrate a different graphics feature of RTX GPUs, including a rare "Lens Cube" that is fully path-traced.

Here's a quick technical rundown of what Portal with RTX brings to the table: the full NVIDIA RTX ray tracing feature-set, including lighting, shadows, reflections, refraction, and global-illumination. Unlike with Quake II RTX, Portal with RTX implements fully ray-traced lighting, which means every light-source across the game is ray traced, and isn't a point-light that casts a stencil shadow. The game also implements RTXDI (RTX Direct Illumination), which allows "countless" light sources, regardless of their size, to cast path-traced shadows and light. ReSTIR GI (Reservoir Spatio-temporal Resampling Global Illumination) enhances indirect light, enduring there are no unnatural dark corners that are not lit directly. This all comes together with NRD (NVIDIA real-time denoisers), an advanced spatio-temporal RT denoising library.



All this ray tracing eye-candy requires a tremendous amount of compute and rendering power, despite NVIDIA giving its GeForce RTX GPUs fixed-function hardware such as RT cores and Tensor cores, that are more capable with each generation of GeForce. NVIDIA understands the importance of making games playable in terms of framerates, even with ray tracing enabled, so they developed the DLSS performance enhancement, which runs the game at a lower resolution than what your display is capable of, and upscales it with minimal loss to image quality, attempting to reconstruct details. Portal with RTX implements both DLSS 2 and DLSS 3 Frame-generation. DLSS 2 should improve performance for RTX 20-series "Turing" and RTX 30-series "Ampere" graphics cards, while DLSS 3 is a brand-new feature for those with the latest RTX 40-series "Ada" graphics cards, as it offers a doubling in framerate by generating frames entirely using AI, with minimal involvement of the rest of the GPU.

In this article, we test and show you comparison screenshots and performance numbers, to highlight the incredible work NVIDIA has done with Portal, and also provide a more in-depth performance evaluation across various resolutions.