SUMMARY: VTX is a molecular visualization software capable to handle most molecular structures and dynamics trajectories file formats. It features a real-time high-performance molecular graphics engine, based on modern OpenGL, optimized for the visualization of massive molecular systems and molecular dynamics trajectories. VTX includes multiple interactive camera and user interaction features, notably free-fly navigation and a fully modular graphical user interface designed for increased usability. It allows the production of high-resolution images for presentations and posters with custom background. VTX design is focused on performance and usability for research, teaching, and educative purposes. AVAILABILITY AND IMPLEMENTATION: VTX is open source and free for non-commercial use. Builds for Windows and Ubuntu Linux are available at http://vtx.drugdesign.fr. The source code is available at https://github.com/VTX-Molecular-Visualization.

MOTIVATION: Protein-protein docking aims at predicting the geometry of protein interactions to gain insights into the mechanisms underlying these processes and develop new strategies for drug discovery. Interactive and user-oriented manipulation tools can support this task complementary to automated software. RESULTS: This article presents an interactive multi-body protein-protein docking software, UDock2, designed for research but also usable for teaching and popularization of science purposes due to its high usability. In UDock2, the users tackle the conformational space of protein interfaces using an intuitive real-time docking procedure with on-the-fly scoring. UDock2 integrates traditional computer graphics methods to facilitate the visualization and to provide better insight into protein surfaces, interfaces, and properties. AVAILABILITY AND IMPLEMENTATION: UDock2 is open-source, cross-platform (Windows and Linux), and available at http://udock.fr. The code can be accessed at https://gitlab.com/Udock/Udock2.

This article presents genetic wave function collapse (WFC), a procedural level generation algorithm that mixes genetic optimization with WFC, a local adjacency constraints propagation algorithm. We use a synthetic player to evaluate the novelty, safety, and complexity of the generated levels. Novelty is maximized when the synthetic player goes on tiles not visited for a long time, safety is related to how far it can see, and complexity evaluates the variability of the surrounding tiles. WFC extracts constraints from example levels, and allows us to perform the genetic search on levels with few local asset placement errors, while using as little level design rules as possible. We show that we are able to rely on WFC while optimizing the results, first by influencing WFC asset selection and then by reencoding the chosen modules back to our genotype, in order to optimize crossover. We compare the fitness curves and best maps of our method with other approaches. We then visually explore the kind of levels we are able to generate by sampling different values of safety and complexity, giving a glimpse of the variability that our approach is able to reach.

Difficulty is one of the major motivational pull of video games, and thus many games use Dynamic Difficulty Adjustment (DDA) systems to improve the game experience. This paper describes our research investigating the influence of DDA systems on player's confidence, evaluated using an in-game bet system. Our hypothesis is that DDA systems may lead players to overconfidence, revealed by an overestimation of their success chances when betting. This boost of confidence may be a part of the positive impact of DDA systems on the quality of game experience. We explain our method to evaluate player's confidence and implement it into three games related to logical, motor and sensory difficulties. We describe two experimental conditions where difficulty is either randomly chosen or adapted using a DDA algorithm. Results show how DDA systems can lead players to high level of overconfidence.

In this paper, we study the link between difficulty and player's motivation in two games developed by Ubisoft®: Rayman®Legends and Tom Clancy's The Division®. We describe a method to estimate players' difficulty over time and link it's time varying effect with players retention. Results confirm flow and self-efficacy theory. Also, for the first hours of playtime, results differ between the two games. We explain that discrepancy with regard to attribution theory : in Rayman Legends, failure can be mainly attributed to the player skills, while in Tom Clancy's The Division, avatar's strength plays a fundamental role and can always be relatively quickly improved.

In this paper, we present a collaborative game designed for Sifteo Cubes, a new tangible interface for multiplayer games. We discuss how this game exploits the platform's interface to transfer some of the game mechanics into the non-digital world, and how this approach affects both the player's experience and the design process. We present the technical limitations encountered during game development and analyze video recordings of play sessions with regard to the play strategies developed by the players. Then, we identify two properties that this game shares with many other games on tangible platforms and discuss how these properties influence both the game design process and the player experience. We advocate that these properties provide players with more freedom and relatedness, while helping to create an easy-to-learn and customizable gameplay, despite their own design limitations.